That is so cute!
She looks fine, really; but I could imagine her a bit less thin. One thing I've deduced with my current guy is that the angle of his pelvis makes it so that his hip bones are visible often, even during one of the rare occasions I've had him a bit better filled-out. Maybe you can take a look at the angle of her pelvis.
I know many people feed Doberman pups a lot more than the recommended amounts on the food bags. I had Oji on 5 and 6 cups of food. Actually, I'm on a campaign to get him less unhealthily skinny so he's back up to 5 cups again.
What is the protein and fat content of your food? What are the first few ingredients? Maybe there is a better food out there for her?