What was the DHEAs before you started supplementing (and remind me of your age)? And what time was the cortisol test (apologies if you had said this elsewhere, there have been a fair few posts about adrenal and/or thyroid issues lately, and I can't keep all the details in my head).

I'm just reacting to the fact that it seems you have been thinking your symptoms were related to adrenals. Now it sounds like you may be having a problem related to aldosterone regulating your fluids, and that is also an adrenal problem. Sometimes people respond decently to synacthen, because that is such an incredibly strong stimulus to the adrenals, but are still not making the optimal amount of hormones. That's why I am asking about the DHEA - if it was very low, it's another sign your adrenals are not making the right amount of hormone.