My dd was a brutal biter, and she cut her first two teeth on the bottom at 4 months. She proceeded to bite me consistently til 7 months when she actually broke a hole into my nipple. OMG, you could put your finger through it!! I am ashamed to admit that I FREAKED OUT every time she bit me hard, although in the middle of the night I usually just woke up witha start and that was enough to make her get back on right. The only way they can bite is if they pull their tongue back into their mouth. If she doesn't let her dawdle on there, or play with the nipple with her mouth, she'll be less likely to get chomped. Dd would only bite after the milk slowed way down. Otherwise, her tongue was between her teeth and my breast. So if she feels the tongue sliding back, she has to act fast. Get her finger in there between those gums and say NO BITE!! in a serious face and tone.
After my dd put that hole in me, I had to keep her off that side for two whole weeks so the hole would close up. It broke her for the most part. I hope all this helps!!