I suggest not moving up. I’m combination feeding too and we moved up nipples and now he’s frustrated with how slow my breast is and refusing it. My LC said they can stay at the slowest flow if it still works. I use a 2 with phillips avent
How old is your baby?
I use the avent 2. I think they have ages for the different sizes. When he was like 2-4 weeks, we were using the 1 and it took him over an hour to finish a bottle, so we switched to the 2 at 4 weeks and it is quicker now