Buy her a small stuffed animal toy or make a catnip toy for her out of the toe of an old sock. My cat loves his nippy toy.

Teething AND discovering her world, much like a human baby! She also may be attempting to "nurse" your fingers, being that 6-7 weeks of age is a bit young to be fully weaned for a kitten. Most reputable breeders will wait 10-14 weeks before adopting litters out. No safe teething tablets, per se, but encouraging "hunting" play (as with a feather on a string), offering small, soft cat treats (you can make them soft by putting a few drops of water on them and wait for the water to soak in), and discouraging the chewing. When my foster kittens start to use my fingers as chew toys, I gently push back. As in, push my finger toward the back of their throat. They don't like the feeling, and eventually, the behavior stops. This does not hurt them. The point is NOT to gag them, just to give them an uncomfortable feeling, kind of like a "that piece of meat is too big for my gullet" feeling.
Hope my suggestions help!
A side note, now would be the time to get a vet visit lined up for baby's first vaccines and check-up!