Redirect his biting you with a toy and get ready for 6 months of biting. He is a dog and that is what comes natural to them do not tap on his noise or do anything in a physical correction just say OUCH or NO and redirect him.
Seriously, it's completely normal and honestly it will probably get worse until the pup is through teething. There are lots of threads on teaching bite inhibition, you'll have to look them up. Try every suggestion, be patient and hang in there, it does get better. Congrats on the new pup!
Redirect, redirect, redirect with toys. Other than that, from what I've learned this is typical GSD puppy behavior. That's why they're referred to as "land sharks", lol. Btw, they do grow out of it. You'll just have some nice trophies on your legs and arms for awhile.
It's true what they've all said. My pup is 11.5 weeks old and my best advice is to keep things handy to stuff in his mouth (redirect) like bones and toys ... to a puppy though, you are the biggest and best toy he has!
There's quite a bit on the board here about 'bite inhibition' ... I dont know how to post links to it, but if you go to the puppy section, you can find the info there.
I'm told they DO grow out of it ... I'll share my bandaids with you!!