I am not a doctor. We're all the cortisol tests 8am? Any serum or just saliva? I would get other testing to support it like antibodies, sodium, potassium and more ACTH. Last a stim test. Then based on those results the doctor can determine if you need replacements.
Sadly fatigue can be so many things!
I did acth, aldosterone, potassium and sodium. Also antibodies for hashimoto which are high.
Then it sounds like you have Hashimoto's. Are you being treated for your thyroid? Your adrenal tests looked normal. Unless you have abnormal sodium and potassium, then I would think (as a layman) that the issue is not adrenal... But they thyroid one can make you feel like crud all by itself!
Sorry, I am out of it, you did not post the cortisol tests with ranges. If you have low cortisol then the doctor needs to run a stim test.