Nancy, this is really interesting. Are you on PPIs? According to what I've read, the normal resting stomach pH is between 1 and 3, and goes up to between 4 and 7 in people taking acid-supression drugs.
I'm asking because I'm interested in the theory that a lot of digestive problems, including gastritis, are actually caused by too little stomach acid. I know, it sounds bizarre, but the argument is that it's pressure on the LES that's at fault, that acid-supressing drugs simply mask or perhaps even exacerbate the condition, and that even a tiny bit of acid escaping can cause heartburn. Some doctors (notably Dr. Jonathan Wright) attribute at least some kinds of gastritis to excessively low acid (gastric atrophy).
Maybe you're too young to have declining levels of stomach acid to begin with. The decline supposedly happens when one reaches middle age. Also, I'm not saying I swallow all of this 100 per cent. But it makes as much sense as any other theory I've heard expounded as to the cause of GERD. Mostly it's, "we don't know."
Good luck to you,