@Fogbound - before I started crashing (PEM), I had severe adrenal fatigue. I think this was caused by years of chronic stress, dating from childhood. I know that the medical profession does not recognize adrenal fatigue as a real thing, but many of them don't think that ME/CFS is real either.
When I was experiencing that severe fatigue, I went to my doctor. This was back when I thought doctors could help us. He gave me Prozac, which did nothing for me but make me feel yucky, and I hated it and stopped it after 2 days. I wasn't wiped out from lack of Prozac.
Then I saw my chiropractor who does muscle testing (or applied kinesiology, often called nutritional response testing). Within a few minutes he found that my adrenals were wiped out. This was the first time I'd ever heard anything about my adrenal glands. He gave me an adrenal glandular product by Standard Process (Drenatrophin PMG) I had to take a rather high dose because I was so weak but after 2 or 3 days my energy started to come back. It felt like a miracle. And I've noticed ever since that when I'm under extra stress (e.g., when my house flooded or my cat had to have emergency surgery, or it doesn't even have to be that bad, any source of extra stress), my adrenals take a hit, I start getting extra tired and when I'm fortunate I realize quickly what's going on and start taking an adrenal glandular again. My adrenals seem to be my Achilles heel. I have a sister who also has trouble with her adrenals although she doesn't have ME/CFS. But she often needs to take an adrenal glandular. We both had a lot of early stressors in our lives. I've used several different products over the years and there are a lot of good ones.
So you could ask your doctor about your adrenals though I doubt he or she would give it any credence. Or you could try to find a chiropractor who does what mine did. Chiropractors who do muscle testing have helped me with several other issues over the issues - I know I would be much worse off without them, though they haven't been able to solve the central riddle of ME/CFS.
And you might need more folate too. Folate has helped my energy and blood work indicated I needed it. But I would look into your adrenals as well.