My daughter is 9 weeks and I'm going back to work when she's 12 weeks, trying to wean her from only breastfeeding to taking the bottle. It's been so hard, she acts like she's gagging everytime we try to give her the bottle, even though it's still my breast milk. We've tried Avent, Nuk, Mam and Tommee Tippy bottles but no luck. Does anyone have any advice on what I should do?