I have come with quite a conundrum that I need solved.

One of my favorite things in mapmaking is making the whole world, including regions. However, another popular thing I have done is making a map of an island; a fictional island on a nonfictional world.

I can't seem to make the right size for the island, due to conflicting nature and habits I have developed. On one hand, I want the island to remain small to keep mapmaking at a definitive state. On the other hand, I want to make it large enough so the main character can oversee not only her job but also prospective economic choices in the future.

To create this island, I have to have at least (according to my friend who used to work for Rand McNally) 4 square miles of land. Reasoning why? Exports of coffee, cacao, and occasional tropical fruits. According to her, I would also have to include 2 square miles for habitation.

Here is the conundrum key.
The map has evolved in my mind ten times. From a simple rock in the ocean to a volcanic island chain, I can't seem to come up with a decent scale for my map. Because I use CC3 predominately, I can't seem the get the right scale because when I do an area calculation, I end up with twice the size I originally intended.

Help would be useful!