Eating too fast may be it along with not eating the right foods. Anything breaded always gives me trouble so I avoid it. I usually take a bite the size of a pea, chew it until it can't be chewed anymore, swallow and then wait about a minute before taking the next bite. I also put down my fork/spoon while waiting. I know it sounds tedious, but maybe that will help.
I am having the same problem. I am only able to eat two bites of ANYTHING before feeling totally uncomfartable. I think I'm too tight because what I eat is coming up just like how you described. I just had my latest fill on Thursday and I think you're suppossed to be able to eat about 3/4 cup of food. I feel like a cow chewing on a cud because I'm chewing so much!!! I don't know, I can live with this until I go see the doc again in 6 weeks. I think right now it's just finding my stopping point.