I agree with rumpled, you need to see a specialist, that is usually an endocrinologist.
But, even then, don't let your guard down. Do as much research as possible. Tests for cortisol, and other hormones, need to be done at certain times of the day to provide the best information. And ideally, the test(s) should be repeated.
Like rumpled, I had some normal tests, some low normal, some mildly high. This was over many months and included all the tests for cortisol, 24hr urine, suppression tests, 8am serum test, ACTH, and midnight salivary swab test. I did not let them get by with just one. That might be harder to push for if your first test comes up normal, but if your symptoms suggest otherwise, fight for more.
Oh, ya, and supplement with vitamin D. Are you anemic too?
If you are shaped like a bowling ball and have a "buffalo hump" (sadly, that is the medical term for it) then you should probably test for Cushing's syndrome which is too much cortisol.
Both too much and too little cortisol cause fatigue and high cortisol messes with your thyroid as well as your vitamin d and many other things.
You can have one or more normal cortisol tests. What time was the test? What type of test was it? What lab? You see, cortisol normally is highest in the morning and goes down in the night - a change in that is a loss of diurnal rhythm and that is usually Cushing's syndrome. Point in time tests should be done at times that are diagnostic like 8am or midnight - be it blood or saliva. Urine tests are good too but sometimes the average can just be deceptive. I was high at night but so low during the day my average was normal. I was sick for 12 years before I was diagnosed and I know others that were sick a lot longer. I just met someone that thinks she has been sick 30 years.
It takes a specialist to test accurately and well.