we use avent bottles, and at 3 months it was time for my LO to move up to size 2 since he was getting frustrated with the slow flow. so i bought size 2 (2pcs) only to find out that the size 1 flows much better than the size 2. i thought maybe because its new and that we have to use it more to let it flow more. i personally help suck the new ones so that the flow can come out stronger. it just gets frustrating that i have nipple teats of size 1,2 and 3 yet i can only use the one nipple teat and have to wash it everytume he uses it for the next bottle. yes i bought size 3 hoping the flow is better, but no the size one flows better. is there a hack on this?
You could take a sewing needle and make the whole in the nipple a little bigger