A map will be available IG soon. I would recommend making your backstory general in it's nature. This allows plot flexibility to work it into stories that we have going on. It's less important to say that "I'm from X town" than it is to say "I come from a farming community".
Here's a PDF of the entirety of the Sheltered Lands. It was accurate up to the end of last year though I don't know if the new plot team has any plans to change it or what those changes might be. Regardless it's probably a good place to start.