That's a beautifully illustrated map. I wish I could letter with such a steady hand!

There do seem to be some similarities to George Martin's continent of Westeros. Winterfell in the North, a dragon island in the east (Dragonstone in Game of Thrones) and rivers stretching in from the west (your Twin Seas versus "The Twins" keeps of Walder Frey and his Red Wedding).

Not that that should have any impact on gameplay or fun! It's hard to create anything new in this world without having it look a little like something that has come before.