He looks a little thin to me but I am no expert. I'd wait and see what the vet says. Given his rough start it might take him a little time to catch up. It's best to keep him lean while he is young so don't rush the weight gain.
What food is he eating? Has he been wormed and rechecked clear of parasites? Does he have good poops?
Ziva GSD 3/7/13
At the Bridge: