My DD bites when she's teething. I have tried a lot of tricks, and nothing has had a lasting effect. I think the thing is that she's not doing it to hurt me, she's doing it because she's hurting.
Em seems to bite mostly when she's teething too. Sometimes it's a boredom thing or a "lazy latch" thing where she's tired but lately she's been doing it A LOT. DH wonders if that's a sign that it's time to wean, which I told him no as she still wants to nurse. I think he just feels bad when she hurts me.
I don't get why people say it's time to wean when they start biting. If they need formula for a year then breastmilk for a year would be the same. I don't want to quit if we can make it through. He's only bit me about once a day and I say "no biting" put the boob away and we just try again later.