You have no doubt solved this picture by now but just in case (and because I wanted to contribute), I wanted to suggest checking the relationship between the legs of the horse and girl. One is too small/big?
Good point Ian, thanks!! At the time I was going for big boots in the name of stylization but ultimately I think it does kind of throw things off. I'm just realizing now that I also need to make her leg shorter - her leg and the horse's leg are the same length. Woops!