Hi our GSD girl puppy was quite a little biter at first, we never encouraged games that made her snatch at stuff, but she would still bite us, I think it's a puppy thing apparently they bite each other in the litter when they're playing. We had her for 5 weeks til she was 14 weeks, and then she went back to the breeders as we were going away for 3 weeks, she spent time with a brother and sister of hers, and when we came back the biting had stopped! He may be teething too.
Also we noticed that she used to play bite our daughter more than us, I think they work out the pecking order of the household (their "pack") and try to work their way up the order!
Goodluck.