Hi there. I use Avent bottles and teats. Liam is just over 3 months old and I'm still using the no.2 teat (for 1 month plus bubs). He seems fine with it but the other day I went out and bought some teats that are variable flow for 3 months plus bubs. They are supposed to be slow, medium & fast flow but no matter which level I try Liam chokes and gags like it's coming out too fast. Has anyone else had this problem with these teats and what no. do you use for your bub of similar age?