Mam bottles

I have been bottle feeding since day 1 and I'm using MAM bottle. Teat size 2 still even though we add the carobel to make the milk thicker she was fine with it. Now she is almost refusing the bottle..I tried teat 3 but is the same. And is too fast. Question, i have been using the easy start bottles ...shall I swap to active? Is there any difference? I'm also considering trying teat size x.