DS is 16 weeks old. The last week he's been messing about during feeds, acting like he's starving, drinking the first 3 or 4 ounces then starting to dribble, push the bottle away with his tongue and his hands, kick and wriggle. I'd started letting him grab my finger as I feed him so he can push the bottle away or pull it towards him, but once we stop half-way for burping I never get him to settle down and take the rest. We moved up to 7 ozs recently once he passed 7kgs and there was no problem til now.
He's still on the 1mo teats, and I wondered if he's getting frustrated at the slow delivery of the milk? He still acts like he's hungry - he tries to shove the muslin in his mouth with both hands but he is a big boy and it's an effort to wrestle him into submission and get the bottle in place - only for him to reject it and go after the cloth again. All the kicking is much more difficult to manage at this age too!
I think the guidance for the second stage teats is 3 months although as with everything all babies are different - we've just switched up for DD at 10 weeks and its made such a difference. It might well be worth a go-does sound like he's possibly getting frustrated and bored to me. Good luck!