we moved ds straight onto size 2 teats as a newborn as he was just being so slow and fussy with the size 1s. he has just started being slow and not finishing feeds again so moved to the size 3s (6m+) at 4 months and he's now finishing 7oz in about 5mins. do you feel your lo is a slow feeder? if so try changing! they might cough a bit at first but soon get used to it!