Your kitty may not have learned proper social etiquette and behavior since you got her so young (7wks), and it seems like she may be biting/nipping at your child because she views your child as a playmate. Most cats have the most energy at dawn and dusk, so the way I'd go about with your situation is providing enough active playtime to the point she is exhausted and panting and simply cannot run or chase, and must lie on her side. The best interactive toy to get is "da bird" or similar wand toys, or even a laser. You'll need to be consistent and maybe do it a few times a day, lasting at least 20 minutes each play session. After a play session, you can allow your child to provide set meals to your kitty, or be the one to give her the treats. As Heather mentioned already, this will provide positive associations with your child and your kitty. Also, remember to never play with your hands or feet with the kitty, always use a toy instead. If you still continue to see your kitty "attack" your child, I'd see if I was also reading her body language correctly, too. Some cats just get overstimulated and if you don't realize it, the cat's only way to get you to stop it is by lashing out abruptly.
Hope it's not the case, though, but it might help if you looked up "reading cat's body language" online, too.