My DS has been falling asleep and taking over 40 minutes to finish a bottle with the medium flow nipple. I switched today to the fast flow and he finished in 15 minutes, staying awake the whole time. How old was your LO when he/she moved to fast flow? DS seems kind of young to me.
Re: When did you move to fast flow?
Six weeks. ?:) ?Babies mouths are all shaped differently; their age actually doesn't have much to do with which nipple size to use. ?As long as he isn't sputtering and appears to be gulping, then it's fine to switch him.
ETA: ?We use Dr Browns, so we moved from level 1 to level 2 at six weeks.