
I have had Shepherds over the years and as all pups are very "nippy" and "mouthy" yours is no exception.
Its good that she is still young and that you can stop this behaviour now while it is in full flow. You need to distract her with something more tempting to bite. Eg, has she got a favourite toy that you can tempt her with? Whenever she is in the mouthing mode put the toy into her mouth. She will be teething soon so its important that you let her have lots of safe things to chew on. You can start by getting her a good solid beef bone from the butchers (watch the marrow though as this causes the runs in pups and some adult dogs) but you MUST supervise her at all times when she has it. Keep her busy, they love being busy :D
When she is nipping you she is doing it for attention, so you have to divert it away from you in such a way that she still sees it as fun. If she still persists in this then walk away and totally ignore the behaviour. They are extremely intelligent and it wont take her long to figure out this is the quickest way to lose your attention. When she is playing nicely and chewing on lots of toys, praise her. I also have a Briard, the breed is renouned for biting and they are very big dogs, he still thinks that he can get away with it sometimes when he is overexcited, be thankful you haven't got one like this :)
They are a wonderful breed and I bet she is gorgeous! I hope you have a happy partnership.