I've done some reading on the topic (namely I've read Thucydides' account), but I don't really understand how Athens lost the war, they were the superpower and Greece, and it doesn't seem to make sense to me. Any help on the subject or advice for further reading would be greatly appreciated
I'm not entirely sure this is getting to the point of your question. Strategically Athens' policy depended on her walls to defend the populace, and supplying the city by ship. That depended on maintaining control of the trade routes and as Athens could field a navy that strategy worked. Athens was able to survive the Sicilian Expedition and the oligarchic coup so long as it had a navy. What finally broke Athens was the loss of the navy at Aegospotami. It was a huge blunder. The Athenians literally went out for lunch, and the Spartan commander Lysander captured the Athenian fleet almost without a fight. Xenophon documents this in the Hellenica.
Triremes did not usually carry provisions. Thucydides makes a special note of the voyage of the Salaminia to Mytilene to reverse the decree executing the people of that city. Th. makes a point that the Salaminia carried provisions paid for by the Mytilenian ambassador to allow the ship to travel without stopping. Usually ships would stop and the soldiers would shop at local markets for provisions. This is one of the reasons Demosthenes was concerned about maintaining bases around the northern Aegean half a century later.
Without a fleet to protect the trade routes and control the allies, Athens wasn't able to withstand the siege, and surrendered in quick order.
Here's some bib on Athenian naval practices: Casson, Lionel. “A Trireme for Hire (Is. 11.48),” CQ Vol. 45, No. 1 (1995), pp. 241-245.
“The Feeding of the Trireme Crews and an Entry in IG ii2 1631,” TAPA Vol. 125 (1995) pp. 261-269.
Cawkwell, G. L. “Athenian Naval Power in the Fourth Century,” CQ Vol. 34, No. 2 (1984), pp. 334- 345.
Christ, Matthew. “The Evolution of the Eisphora in Classical Athens,” CQ Vol. 57, No. 1 (2007), pp. 53-69.
Gabrielsen, Vincent. Financing the Athenian Fleet: Public Taxation and Social Relations. Baltimore: Johns Hopkins University Press, 1994.
Hammond, N. G. L. “The Narrative of Herodotus VII and the Decree of Themistocles at Troezen.” JHS, Vol. 102 (1982), pp. 75-93.
Morrison, J. S., and J. F. Coates. The Athenian Trireme: the History and Reconstruction of an Ancient Greek Warship. Cambridge: Cambridge University Press, 1986.