Breastfeeding and biting nipples

Stephanie
My daughter is about eight months old and she has started biting me while she is nursing. I know that she is teething but that doesn't take away from the pain that it causes. I am starting to get frustrated because my nipples are so sore. Any time I try to make it clear that her biting me is not okay she just laughs. Help! I don't know what to do....
P.S. I do pinch her nose just so she will let go, otherwise she will bite and pull as far as she can.