I am having a nightmare going from breast feeding to mixed feeding. My daughter is now 14 weeks old and we have been trying her with a bottle from 8 weeks. She cries and gulps air and ends up having lots of wind. I've tried Avent, Nuk & MAM teats but it makes no difference and I have tried using expressed milk, formula milk and a expressed/formula mix. Been out the room/in the room and other people have also tried without much success. Most times she only takes a couple of ounces. Any tips?