Hi, My DS is currently having 3 bottles a day, ...

Hi, My DS is currently having 3 bottles a day, but rarely finishes them. In fact, I don't think he'd care if he didn't have them at all!! I'm thinking of dropping him to just 2 bottles, but is this too soon?? I think they usually go to 2 at about 12months?? OR, he is still on size 2 teats (avent), so is that the issue?? Should I just up the teat size to a 3?? What are people's thoughts??