J.P.
I had the same problem around the same age with my son. It seemed that he didn't realize he had teeth and that they hurt! I think he was just testing the new things in his mouth, and when he bit the bottle, it wouldn't matter. It mattered on me though! A few times, he bit so hard I started bleeding. When he would bite, I would say NO BITING really seriously and a bit loudly. It got his attention, and I would let him nurse again, but if he bit a second time, I would repeat the NO BITING and delatch him carefully. I wouldn't let him nurse again for about 10 minutes. Everything I read said they bite when they are finished eating, but he would always eat again after the 10 minutes. After a few times, he got the idea! The only issue now (very occasionally) is sometimes when he's pulling off, his teeth scrape against me. That's another ouch, but it's totally accidental, so I don't do anything.