My 3 month old been struggling alot lately when drinking milk. It starts out fine then when we stop her halfway to burp, trouble begins. She will yell and arch her back refuse to let us sit her up to burp. I usually then either carry her upright over my shoulder which she calms down or continue to try feeding her. Sometimes she carries on drinking but not without pulling away from the bottle after a few sucks and yell and arch back again until slowly coax her to finish. At times after struggling for some time she will cry n cry, get tired and fall asleep without finishing the bottle. On good times she will finish after like 30-45mins. What's going on? Is the teat too slow for her? I'm using 0+ and 1m+ teat now should I upsize?