Did both of you try "Dr. Brown" bottle? I use it when my bb is 3 months and it is really better. This bottle can find in "bebe dreams" or "Jusco" but it is quite expensive, cost around$65-70?(I forgot). May be you can consider to buy 1 bottle first and try if it is work. Hope this can help both of you!
littlewhite_amy,
Dr. Brown is only a special design milk bottle (like e.g: pigeon, Nuk,etc..). The design of this bottle is: there is a special tube inside the bottle and when the bb suck the milk, the air can go through to the tube to the bottom of the bottle and won't go inside to the milk. That's why when the bb will not suck the milk together with the air and because of this it can help the bb burp (let the air come out from the stomach) more easier. As "Dr. Brown" is only a bottle and can use even for a new born BB.
Last time my bb experience also the same problem and my Dr. show ask me if I want to try "winddrop", as the Dr. said this is safety and won't have side-effect (I never try). If you want to try, how about consult to your Dr about this?