Alterations question....

I have the Maggie Sottero Grace Marie, and there's a 4 inch gap at the bottom of the corset. I feel like part of the problem is that the dress is too long in the bodice (I'm 5 feet zero), and the bottom of the corset is therefore too low and at a wider point than it should be.

If I sit down, I'll be sitting on the bow of the corset. Is that where it should be? It seems like it can't be right. Can they shorten the bodice of a corset back dress and raise the whole dress that way?