She bites

We've got a biter on our hands. I do at least.

Nursing moms out there!!!! HELP! She's been biting me at nursing time every single time since last night. What's up with this?! Where did she get this from? And more importantly, how do I make her stop?

I've tried the startlement (and by that I mean I was startled from the sudden pain and yelped out loud startling both of us- which she thought was funny). I've given her the stern NO! over and over again (which she also finds humorous). I've even held out from nursing a while until its necessary but nothing is getting through to her.

I've already been thinking about starting to wean her now that she is past a year old, but honestly I have no idea how and don't want to make a rash decision like that.

My boobs and I would appreciate any advice you could give me. P.leeeease!