Great, so the cortisol test confirms adrenal fatigue. It can either primary where the adrenals are actually fatigued and the traditional supplements such as adrenal cortex extract, etc. can helpful, or it's secondary, where it's a signaling problem in the hypothalamus and pituitary. It will look the same on the cortisol test.
I believe I have the secondary kind with the signaling problem, or at least the traditional supplements are too overstimulating and not helpful. The hypothesis I've heard regarding the signaling problem is that it's due to low glutathione.
I also had autoimmune thyroiditis - same deal as what bertiedog is saying - my TSH looked normal but my antibodies were sky high. Most doctors overlooked this except for my good doctor who figured it out by doing a complete thyroid panel. I was on Armour Thyroid for about 13 years.
I say "had" because I have recovered from that. My complete thyroid panel is normal and I no longer need any medication. I believe this is due to somewhere between getting my last mercury filling out and starting methylation treatment. I did both around the same time. About a year and a half later, my thyroid recovered. Note that both removing mercury and doing methylation will raise glutathione.
My adrenal cortisol test was a lot worse than yours for over a decade, but the same kind of pattern - low during the day and slightly higher at night. What has been helpful is replacing the electrolytes which are lost when your adrenals aren't working right. That would be salt, magnesium and potassium. Essential fatty acids such as fish oil may also be helpful if you have dry, gritty eyes and dry mouth. This will help stop getting more cavities due to dry mouth (ask your dentist if they think your mouth is dry).
I only needed salt when things were worse and I was craving salt or salty foods. Then I got to a point where it was just magnesium and potassium. I needed thousands of mg of those dosed four times a day with double the amount of magnesium at night to stop twitching feet from disturbing my sleep.
When I went through an extremely stressful period, Dr. Wilson's Adrenal Rebuilder was helpful. This has dried glands but no hormones, so it gives you glandular nutrients. I was only able to take about 1/4 of a pill, and only for a few months. Beyond that, even that was too overstimulating.
Last summer, I retested, and my adrenals were 50% better. I recently did one partial round of Cutler frequent dose chelation for the mercury, lead and arsenic that I have. My need for magnesium and potassium has dropped dramatically in the past 6 weeks from thousands of mg to about 50 mg each for magnesium and potassium, so I believe my adrenals have gotten another notch better.
Soooo, given all of that experience, I would suggest doing a hair test for mercury and other metals. See my signature link for info on Cutler chelation and how to do the hair test and how to get it interpreted. It's only $85, so it's a no brainer for most people unless they have extreme financial issues.
If you decide to do chelation, I suggest only doing frequent dose chelation. I've done traditional types of chelation and gotten worse. I've heard other people report the same thing.