I think your prototype 15th century market town has some of the key elements, but it is too small, and its distribution of building uses would indicate an unsupportable economy.

In general, your town does not have enough space for a population large enough to fund the castle, church, the walls, and support the businesses.

These pictures: http://imgur.com/a/WVXXK#P81mJCe

Show some views of the village of Lussan in the south of France. This was a village of about 450 people, not a market town, but it was able to fund a castle, town walls, and a church. The images show two views of the castle (which guarded the road up into the hill top town), the town wall, and an aerial view of the village. You will see that the size of the village, and the number of houses is much larger than yours, and this is just an agricultural village, not a market town.

Here is an aerial view of Uzes, in the South of France: http://www.agefotostock.com/en/Stock-Images/Rights-Managed/TIP-006GAR07323

This was a market town, or small city. In this picture you can see three castles (the tall towers near the center of the town; one the tower of the Lords of Uzes, one the tower of the Bishop, and one the tower of the town guilds (later of the Kings of France)). There is a cathedral and bishop’s palace at the lower left of the town. There is a second large church at the upper left of the town. The circular belt of trees surrounding the town is the path of the old walls (now a road). The large, almost rectangular patch of green near the top of the view is the “Place aux Herbes”, which is the market square. Again, note the size, and the number of buildings needed to house a population large enough to support this sort of infrastructure.

Finally, here are some pictures of the Bastide of Monpezier in the South of France. Bastides were new towns, purpose built in the 13th and 14th centuries. They were usually built on a grid street pattern (like your prototype, but unlike older towns such as Lussan and Uzes).

http://www.abelard.org/france/bastides.php

Monpezier had a town wall, a church, a market square. If you look at the aerial view you will see that again, Monpezier has many more residential buildings than your prototype.

I think that your prototype market town needs to be larger, with many more houses, to be able to afford the infrastructure and support the businesses which you have included in it.

I also think you may want to re-think your mix of businesses. The blacksmith, tailor, tavern, bakery are fine (a town of any size would have several bakeries). Barber, Pharmacy, Bank (Uzes had a mint, but banks were not a feature of medieval towns), are more questionable. Medieval towns generally had more workshops (like the blacksmiths) such as weavers, dyers, fullers, carpenters, coopers, masons, potters, butchers. Fletcher is the right idea, but, I don't think correct. Arrow making was generally done in people's homes as piece-work, I believe, not in dedicated workshops. A merchant town might have needed more warehouses. A bath house would be unusual (though in the South of France a 'lavoir', or place for washing clothes might be a feature, often close outside the town rather than in it. See here:

http://www.fond-ecran-image.com/en,Goudargues-sur-les-gorges-de-la-ceze-cad,galerie-membre,lavoir,goudargues-sur-les-gorges-de-la-ceze-cadjpg.php

for a picture of a lavoir in Goudargues, France).

If there was an inn (they were less common in Medieval times than one might think) it would need a stable nearby.

If the town were large enough, there might well be one or more monasteries either in the town or nearby. (Uzes had several not far outside the walls.)

As you indicate, your town will need one (or likely several) wells (or more likely, fountains, in the South of France) for people to get their supplies of water.

In medieval towns, retail shops were less common than workshops (most people shopped at the weekly or bi-weekly market where producers from the surrounding countryside would set out their wares on trestle tables).

The town economy was mostly based on artisans and craftsmen, merchants, some retailers, administrative functions (religious and civil), legal (the court), the market. These were operated by master craftsmen, journeymen, apprentices, laborers, clerks, and supported by domestic servants (the higher servants of the lord or bishop might be some of the wealthier inhabitants). Primary products (wheat, flour, fruits, vegetables, wine, fish, animals, lumber, stone, clay, wool,) were produced in the surrounding countryside and brought into the town. Much of the town economy was based on the skilled conversion (the villages around were often capable of less skilled conversion) of these into secondary products.

To make your town’s economy work, you need a lot more housing for the population. To make your town's economy more representative of the period, add workshops and warehouses and prune the amount and types of retail.

Are you doing a mock Dunluce village?

The Department of Environment NI published a book a couple of years ago about the history of the castle and the ongoing archeological work there. It's worth a read, as it's very thorough (in that it covers pretty much everything known up to that point, more work has since been carried out). It's called Dunluce Castle: History and Archaelogy by Colin Breen, who lectures at the University of Ulster in Coleraine.

My copy is at home, but if you're interested I could perhaps scan some of the relevent pages for you later this week.

I'd also point out that the village is from ca. 1600, so it's slightly later than you're describing. The reason the village is not protected from the road by the castle is twofold: first, the castle formed part of the holdings of the MacQuillans, and their fiefdom known as 'the Route' - with its basis in the much older Hiberno-Scottish kingdom of Dal Riada. As such, the natural orientation for defence was out to sea. Nearby castles such as Dunseverick are similarly arranged. Second, the town grew up after the castle changed hands, and was an afterthought - the town was there to supply the castle, not the castle to protect it.

If you've further questions about early modern Ireland I'd be glad to help (or at least point you in the right direction).