This is of course an uneducated opinion, but for what it's worth.
I'm bothered by the lighting of the model. You have the sun in the image as a light source on the left, but having light coming from behind her implies that in the picture itself there's another light source. I'm caught wondering what that other light source could be, especially since you have it broken up as though it were sunlight from perhaps another sun? Does that even make sense? I'm having trouble articulating what I'm thinking...