I'm glad you've gotten your own thread. After I had my Nissen, I began "burping" immediately, even in the hospital. Like you, I was told I wouldn't be able to burp. I really think it's more the stomach burps for us...I can't force a burp out anymore, but I just have to wait patiently until my stomach is ready to burp itself.
I was concerned when I found I could burp, since I was told I wouldn't be able to. Another surgeon in the group who signed me out of the hospital said that I may be able to burp and that would be a good thing. Your stomach burping will help you keep from getting as bloated. My problem has been when, at times, (long after the stage you're at) I eat too much and there is too much pressure on the wrap to allow it to burp. That's the only time I get bloated.
I was worried that burping was in indication that the wrap was too loose, and I wondered that if air could escape acid might, too. I was told that air could escape without allowing reflux to occur. And it does.
As far as pain after eating too much...Keep in mind that your stomach was pulled, stretched, and wrapped around your esophagus. Those things still have a lot of healing to do. I was told long ago that it took 6 months for the majority of healing to occur, and a full year for the rest. Patience...it's normal to have pain at this point when you overeat. Your eating plan sounds very sensible. Small amounts more often is the ticket.
Again, glad you've joined us!