I feed my 60 lb. dog less than 2 cups a day. She gets a special natural food that has more nutrition per volume than commercial foods, but not that much more.... Puppies may need a little more for growth... but not that much!
If you are going by the feeding suggestions on a commercial puppy food bag, you are expecting him to eat a WHOLE lot more than he needs or wants, in my opinion and experience. The puppy looks fine in the photos. Let him eat til he stops then remove the rest. Otherwise you will end up with an overweight dog, and I promise you, there a a lot of reasons you do not want that.
Your vet said she was fine. If you are that concerned, take her back to the vet, find out what she weighs and what her likely adult weight will be, and weigh her at home every month or so. Then you can better gauge how much you should feed.
I cannot believe a dog that size needs 4 cups a day of any kind of dog food.