Bottles

So we have used Avent natural since birth. She’s almost 4 months now. We are still using the 2 month nipples cause the 3+ has too much flow and she chokes on it. So sometimes she does fine while feeding but other times usually in the morning she fights the feeding so much and doesn’t drink as much. I’ve noticed that the nipple is more flexible than it used to be so she will push it around with her tongue. We have tried two other bottle types, dr browns and tommee tippie and those were both a no go. So I’m trying to figure out if we need to get some new 2 sized nipples or if we need to try another bottle type. We go to the dr on feb 20th for vaccines and I will talk to her dr about it but was wondering if anyone had any similar experiences and if anyone has any suggestions?