Which anti colic bottles are you using? I'm a second time mom with a 3 week old who is really struggling with bottles. With both mam and tommee tippee she sounds like she's taking on too much air and ends up crying in pain. Was given a NUK bottle to try but the flow is way too slow for her, she's taken that long to feed on it this morning that she was hungry again within 30 minutes. I've tried looking into the next size up, which would be 6-18m from the website, but they seem impossible to find. So staying on those don't seem to be an option.