Question on Burping

I have severe heartburn and have been diagnosed with GERD & hiatal hernia.

Trying a no meds approach at the moment.

There's something that I can't figure out.

I've been told by doctors the cause of my GERD is likely the hernia and the only solutions are meds or surgery. OK, standard response.

But reading around I see one popular theory that in some people with GERD intra-abdominal pressure (maybe caused by SIBO or some other issue) forces the stomach up compressing it and causing the hernia / GERD.

This is my question. Every time I burp after a meal, I get bad heartburn. I can just feel the acid coming up through the LES with the burp. So why don't people without GERD have this problem? Everyone's LES has to open to burp. And non GERDies should have plenty of acid in their stomachs too..

This makes me think that my stomach could be being compressed from below.

Any thoughts?