Help!

I have a question I have a fast letdown and produce a lot of milk I've tried pumping before I feed her so it's not shooting out but it makes me produce even more and makes my boobs kill but if I don't after a minute if such she gags I take it out and it's a full stream that I have to put a towel over till it's done and it will constantly do it I've noticed she's be one gassy and has been starting to spit up is there any other things I can try to do to help I've tried changing nursing positions with no luck also