I don't know if this will help, but get a friend or someone to analyze you while you are eating. My mother used to really fuss on me because I'm terrible about
sipping/slurping when I drink from a cup. Some people say that drinking from a straw is bad about
inducing gas, but I don't think that it is, unless you try to clean the bottom of the cup like a vacuum cleaner with it, lol. If you have soup a lot, you need to make sure you don't sip it either. Or noodles if you eat them Japanese style (lots of slurping). I know you're supposed to daintly sip or slurp your tea/coffee, soup and noodles, but that's bad for getting air in your G.I. tract.
And I assume you never drink anything that's carbonated? That'd really gas you up, maybe even for a good while after you drink it. My mother used to burp non-stop when she drank Sprite and so evenutally had to give it up. Funny, other colas didn't make her burp nearly as much; I guess Sprite just has more carbonation. My great-grandmother just belched constantly regardless. Sometimes some people just do it for no particular reason.
I know it's not fun to have your sleep disturbed, but at least it's not staying in there, trapped, and giving you loads and loads of pain. Better out than in.