She is not teething...puppies do not start teething until about 4 months. She is being a puppy. When puppies play with each other they play with the only thing they have....their mouth. So this entails lots of biting and growling and nipping. So your puppy is being a normal puppy. There are no other puppies around, just you, so she is experimenting on you.
What you have to do is teach the pup that it is unacceptable to put its teeth on skin. There have been various threads here on puppy biting, so searching the archives may do the trick. Here are a few links to get you started:
http://www.rottweiler.net/forums/sho...ghlight=biting http://www.rottweiler.net/forums/sho...ghlight=biting http://www.rottweiler.net/forums/sho...ghlight=biting
BTW, I never use the word 'No' with a dog...they end up out tuning it out...kinda like kids and husbands...LOL! I always use a stern "NEIN!" for knock it off and if I mean business its "PFUI!" (fooey). For a young pup, the best way to teach them is a firm sharp, "AH AH"! They do not like that noise and it usually makes them stop whatever they are doing immediately.
I have to admit it sounds like this pup may have some very nice working drive from how you have described her. Where did you get her? Have you considered working with her? At nine weeks she is the prime age to start tracking and ragwork and imprinting her for adulthood.