That is almost 34 pounds, and she is 4 months old. Sounds good to me!
Hans was 33 pounds at that age.
How big are the parents?
Can you post pics of her from the side and from above?
3 cups a day seems adequate to me, depending on the type of food. You don't want a fat GSD. It is terrible for their joints.
Here is Delgado's weight:
Originally Posted by Shade
Delgado was 20.6 lbs at 12 weeks and 30.6 lbs at 16 weeks on the vet scale, so exactly 10 lbs in two weeks lol. He was always very lean and both parents are within standard.
As others have said, keep a eye on his waistline and strive to keep him lean to reduce stress on his joints as he grows