I have a 3 month old, doing the same thing. ( I have 3 older kids I didn't breastfeed, and a 2 year old I did breastfeed.) My 2 year old also did this, and I had been going to La Leche League, and they said to push her against my breast and of course wanting to get air she would release my nipple! It did work. She quickly stopped doing that. Then she got teeth, and still, she didn't bite. But around 11 months old she started to bite again and with all those teeth MY GOD did it hurt. Three separate times she bit down so hard I saw stars, each time I wasn't able to stuff her face into my breast because she'd bit hard and fast and didn't clamp down. Each time I hollered out in agony "OUCH THAT HURTS" and frightened her. She did it three times, three separate days. I finally QUIT breastfeeding because I was in fear of going thru that much pain again! I mean, it was serious, I had to check to see that I still HAD a nipple, it was that intense! Not to scare you! But yeah, while they just have gums and they're doing that clamp down/yank your nipple off almost kinda thing, the best way to get them to let go is just push their little face right into your boob so they'll let go, it works every time :)