What are you feeding? Four cups sounds like a lot. Maybe try a higher quality food. Less fillers, you feed less, pup receives more nutrients, poops less.
Liking herself raw is not good. Could be food or environmental allergies, skin infection or yeast infection. I'd have it checked out by the vet, but if food related, a change in food could solve both issues of her eating a lot and still being too skinny, and licking herself raw.