I highly doubt that you have supply problems if you've been successfully nursing for over 8 months. What you express is no indication of supply. Pumps try to simulate baby suckling, but many women don't respond that well.
As for the biting, if she is biting, she's not nursing. It is physically impossible to bite and nurse at the same time since her tongue has to be wrapped around your nipple. When she does, just unlatch her. Try not to yell or react. That could make the problem worse. Eventually she'll learn that if she wants the breast, she can't bite.
I promise, it doesn't last forever. My son bit for a small time too. I noticed it was mainly when he was nervous. Other than the occasional slip up here and there, he's still happily nursing and knows not to bite me.