Hi C.,
Both of my boys got their first two teeth at 4 months. The next two at six months. My 11 month old now has 7 teeth. Babies start teething a good month before the teeth actually poke through, so your daughter could very likely be teething.
I breastfed both boys, first for 17 months and my 11 month old is still breastfeeding. I have been bit quite a few times, especially during teething periods. What I have done if I feel him biting down is poke his cheek and say no biting. He always stops to listen. I repeat this if I have to and it seems to work.
I have also screamed out before out of pain and shock! This got his attention too. If they are able to bite down they are not feeding properly because their tongue should be cupping the bottom of your nipple covering any teeth. If your baby is biting down or kind of playing, it is probably good to take her off momentarily and try again to see if she is done.
You mentioned having supply issues. She may bite down when supply is gone to try to get more. I encourage you to keep breastfeeding! Even if you are by, you are both still bebfitting from what she is getting! Have you seen a lactation consultant? You may want to check out Milkalicious in Aliso Viejo. I was there last week and they are amazing!
Best of luck!
H.
Birth Doula
Full Bloom Birth