Just want to correct one of the dates; the first European land conquered by the Turks isn't Istanbul (1453), it's actually a small part of Gallipoli (1352). Istanbul was taken 100 years after their first entrance to Europe and after they began to rule nearly all of the Balkans.
About the question... I don't feel knowledgeable enough to answer that.
I would like to add that the idea of an ‘Islamic Empire’ taking ‘Spain’ is also a somewhat of a misunderstanding of the circumstances regarding the ‘Spanish’ conquest (I use the term very guardedly as Spain did not exist for several centuries after the events).
I recently went into great detail concerning the events of 711/712 in a separate post (https://www.reddit.com/r/AskHistorians/comments/e3cf6o/the_spread_of_islam_and_the_conquest_of_alandalus/?utm_source=share&utm_medium=ios_app&utm_name=iossmf) but summarised briefly:
There is every indication that the invasion of the Visigothic kingdom was not part of some grand idea of Muslim conquest but predicated upon local politics and the nature of the failing state that was Visigothic Iberia.
And yet even after the consolidation of the region by the representatives of the Umayyads it was never a fully stable region, rather an unstable province far from the centre of power.
It faced several rebellions by Berbers against Arab authority and less than 40 years after the end of the conquest (ending in 718) broke away from the Caliphate when the Umayyad ruler Abd al-Rahman I fled here after the fall of his dynasty and the rise of the Abbasids and created in effect the independent Emirate of Córdoba. In time this became the entirely separate Caliphate of Córdoba, and while its influence spread to North Africa, it was in no way whatsoever part of the much larger Caliphate based in Damascus or Baghdad.
Thus when this state failed and descended into the Taifa’s they were weaker, divided and unable to stop the various Christian powers from taking them. The reconquista never reclaimed a single inch of land from any great Muslim empire, so the idea is somewhat moot.
The Turks very nearly didn’t, in all honesty. It lost its holdings in continental Europe gradually over the 19th century as various portions declared independence or were absorbed into Russia and Austria-Hungary. By the onset of WWI, the Ottoman Empire had lost all of the territory it held in Europe, save for the portion of Thrace that it still possesses today (this was the boundary established after the second Balkan war). This was one of the reasons the Ottoman Empire joined the central powers: they were hoping at a minimum to reverse the independence of Greece (which chose to remain neutral until 1917, although this caused severe internal discord), and possibly Bulgaria (which shrewdly also joined the Central Powers in early 1915).
In the treaty of Versailles, the Turks were to be given a mostly landlocked rump state about a quarter of the size of the current Republic of Turkey, with a capital at Ankara and occupying the central Anatolian Plateau. Istanbul and the area around the Bosphorus were to be an international zone; Greece was to get the Aegean coastline (they also desperately wanted Istanbul, which was envisioned as the capital of “Greater Greece”); Italy was get a portion of the Mediterranean coast opposite Cyprus, France would get mandatory power over a section of the southeast bordering Syria, and the United States would become the mandatory power for an independent Armenia in what is now eastern Turkey.
However, by 1921, only Greece had actually moved to put this plan in action. For its part, the Turks found themselves in a de facto civil war situation in which Mustafa Kemal (later Atatürk) had set up a new government in Ankara, to which most of the former Ottoman military gave allegiance. (The Ottoman government, remaining in Istanbul, was largely ignored—this is why it’s not considered a civil war. There were two rival governments, but one had pretty much no power and they weren’t actively fighting each other). Kemal’s government gained legitimacy by driving the Greeks out, culminating in the burning of Smyrna/Izmir in September of 1922.
They were able to renegotiate the terms of their surrender in the Treaty of Sévres, which recognized the territorial integrity of what is now the Republic of Turkey, and renounced claims to lands outside of it (in the 1950s the Turks claimed this didn’t apply to Cyprus. That’s another story). For countries other than Greece, the interest in territory wasn’t that strong. The US hadn’t joined the League of Nations, and Armenia had been incorporated into the USSR, so the question of the American mandate was moot; Italy had renounced its interest in the southern coast; and France was having enough problems organizing its mandate in Syria as it was (in fact, the Hatay province would later vote to secede from Syria and rejoin Turkey in the early 1930s).
Greece and Turkey settled their differences through a gentleman’s agreement that resulted in a ‘voluntary’ population exchange in 1923-24 (i put this in quotes because it really was between the leaders; it was not ‘voluntary’ by any stretch of the imagination where the people forced to move were concerned). 1.5 million Christians living in Asia Minor were declared ‘Greek’, and 750,000 Muslims living in Greece were declared ‘Turks’ and they were ‘sent home,’ despite the fact that many of them didn’t speak the language or have any connection (ancestral or otherwise) to their newly identified ‘home country.’
The tl;dr is that the Turks fought very hard in the early 1920s to hang on to the territory they currently have. It’s now known in Turkey as the War of Independence (and in Greece as the Anatolian Catastrophe), and it legitimated the government of Mustafa Kemal (Atatürk) as the rightful government of the new state.
I'm sure there are people who are more qualified than me to comment on this, but I've done a far amount of reading on the Ottomans and hopefully that means I can impart something useful here, though I'll be starting from 1526 instead since, from there, there were no Ottoman substantial conquests in Europe. I'll begin by laying out the 4 phases of Ottoman history i've identified from my reading (remember, I'm by no means the most well versed in it), and then state what I believe to be the key differences between Ottoman Europe and Muslim Spain that saw one hold on for far longer than the other.
1526 saw the collapse of the Kingdom of Hungary into 3 separate states; Habsburg Hungary, Ottoman Hungary, and Transylvania. Despite initial attempts to unify the first and last, fate ensured that this never occurred and Transylvania effectively remained an Ottoman puppet throughout its existence. An attempt to occupy Vienna in 1529 failed, with a joint Spano-German force driving off the Turkish armies after 3 weeks. After this, the border settled down into a long period of sporadic raiding, skirmishing and sieges with intermittent flare ups. Throughout this period, the military balance was in clear favour of the Turks, with the Austrian Habsburgs even paying them tribute to maintain an ostensible truce. Failure to do so was one of the reasons, cited anyway, for the beginning of the Long Turkish War. The Habsburgs were fortunate that the 30 years war ran at the same time as some of the worst governance in the history of the Ottoman empire, since they would have had precious few resources to deal with any Turkish invasion on the scale of 1529 or that of 1683, and the chance of voting a Reichskrieg would, in my opinion at least, have been next to zero.
I would say this period ends in 1699 with the Treaty of Karlowitz. The Habsburgs have conquered Hungary for themselves, and will hold onto it for the next 220 years, and the direct threat which the Turks held to them and central Europe was effectively removed. Whilst their gains in the Turkish war of 1716-18 were lost in 1735-38, and the Russians had lost their outlet at the Sea of Azov in 1707, the Ottomans could no longer be said to be the existential threat they once were.
Saying that, however, they were still a viable power for the next eighty or so years, as shown by the fact that they had successfully checked both the Austrians and Russians in the war of 1735-39- something unthinkable a century later. Indeed, whilst they lost the other wars of the century against the Russians, ceding territory north of the Danube and the Crimea, they were still more or less a viable power. There were issues with the Jannisaries, yes, and Selim III would ultimately be killed for his attempts to reform them, but overall the Ottoman army was still, at this stage at least, a match for its European counterparts. This is a somewhat transitional phase, with the Turks still able to hold their own, to a degree at least, yet not being the same power that they previously were.
This, however, ends rather abruptly with the Russo-Turkish war of 1806-1812. Alexander I, taking advantage of the free hand given to him by Napoleon in the Treaty of Tilsit, occupies Bessarabia and Bucovina, and is arguably stopped from imposing further conditions only by the gathering storm that is the Grand Armee and the Invasion of Russia. Yet barely two decades later and Russian intervention in the Greek War of independence, alongside Britain and France (though these two powers intervened for drastically different reasons), sees the Russians detach Greece and occupy the Danubian principalities, though the latter are later released.