Having sifted through all of the comments here, and having eyeballed several GSD's around my neighborhood... I think your dog is just about right.
There is going to be some variation, of course, but I don't think your dog is going to be extra large or extra small.
You should have a nice-sized GSD when fully grown, athletic and nicely proportioned.
7 Month Old Shepherd by: Brad
My shepherd is 7 months 10 days and weighs 77 lbs.
Hawkeye is Growing Fast by: Anonymous
Our puppy was close to that at 6 months so I think you'll be fine. Are you feeding him puppy food? We never fed our dog puppy food as recommended by the breeder.