Switching a dog from puppy kibble to adult kibble?

I switched my GSD from puppy to adult food early because he was gaining too much weight too fast. Could not feel his ribs. Personally I would come closer to believing the breeder than a vet, as some vet's don't know everything. A female GSD should weigh anywhere from 55-80 lbs roughly and it can vary depending on whether she full German bloodline or American. You should be able to feel her ribs fairly easily under her skin. Adult food is fine. I have mine on a grain free dry dog food, Taste of Wild, because he has food allergies, which is common in them also.