
You are saying she is fed the amount for a grown dog of her size, and as is most peoples experience adolescents generally need more food than the adults of the same breed.
Now the difficulty is guideline amounts.
Most people I know have never fed their dogs what is a guideline amount for most foods.
with my own breed (same size as your pup is expected to be) it is something like half to two thirds what is advised, with youngsters getting proportionately more, but no where near the amount suggested, but this is a breed trait, they re good doers. A similar size breed say my friends Border collies get nearly twice what my dogs do to keep a good weight.
So I would contact people experienced with your breed for advice regarding what the average fed the diet you are feeding would be expected to need.
I would still say if the pup is ravenous and thin then it isn't enough. If the consistency of the output is normal (not soft, but not bullets) then she needs more, overfeeding or food not being digested properly results in voluminous loose stools.
Unfortunately even though I have raw fed, and mixed fed, currently I feed dry complete, and have never reared an adolescent entirely on raw, so can't advise re amounts with my own breed which may not be relevant for you anyway.
You do not seem to approve of the food fed to the puppy by the breeder, but was she a good weight for a puppy when you got her, and were their other dogs in good condition?
You may have a preference for a different feeding method and products, but if you had faith enough in their ability to breed and rear your puppy well then their advise may well be worth having, at least as a guideline to amounts, frequencies, and general stages of development re weight.