Our Shepherd pup is just a few weeks older and may actually be slightly thinner looking. With the breeders recommendation we keep her bowl with high quality food all the time, she eats as much as she wants, when she wants. We actually mix some puppy with adult food, dry.
As with most, it's healthier on the lean side. It takes a little getting used to compared to a Lab type body/puppy shape too, they are on the lean side.