Hi Peter,
You'll just have to try the water out and see how it goes. Sometimes, water is the hardest thing on my GERD. For some reason, it causes me to have alot of esophogeal spasms. I think what happens is that it mixes with the stomach acid, and brings it up the esophogus. But then there are times when I drink alot of water at night, and it doesn't seem to bother me.
It sounds like you're doing all the right things. But I think there's some elements to this disease that we can't control.......like perhaps a neuro-muscular-type connection, so that our LESs stay open when they shouldn't.....even when we're doing the right things. Also, I think women have alot of hormonal "interference".
Are you keeping the head of your bed elevated? That may also help when drinking water at nighttime. And, of course, not all water is created equal.....so you might have to look around for a water that is the least offensive to your system.
I hope it's not a life-long problem, but I think it might be for some of us. So much is dependent on how and what we eat, our body make-up, our own particular biochemistry, etc. I seem to have waves of it. At other times, I can abuse my stomach, and it doesn't seem to mind.
The bad thing is, when I'm doing fine.....I think I do those things that make it come back! For me, the absolute worst thing seems to be using antibiotics. Good luck to you.