Laura at nine months old kittens aren't teething. They get their full set of adult teeth by the time they are 7 months old. It is likely that this kitten needs some interactive playtime with a toy on the end of a fishing pole, a long feather- or something that keeps your fingers out of reach. If you have been playing that cute game of fingers under the blanket,you will need to stop playing it, for cats are not dumb they understand that even if the hand is under the blanket at the time, they know right where that creature belongs, on the end of your arm.
She might be biting out of pain, so it is a good idea to take her to the vet and have her checked out as well. Biting is a common stimulus to pain in kitties.