Peggy,
Hang in there and keep your confidence and belief that you'll see those better days ahead!
You know of course that making sure your thyroid hormone therapy is best optimized for you is most important. You may already know yours has been adjusted to the best level for you.
Afterward, if you still have unresolved symptoms of fatigue, etc..., you should have very thorough blood and possibly saliva testing, to check for other problems.
You likely have had most of these tested but includes adrenal, sex hormones, CBC, glucose, electrolytes (magnesium, potassium, sodium, chloride etc...), tests for systemic inflammation and autoimmunity (ESR, ANA).
Unfortunately it sometimes takes a lot of testing to rule out other causes. If you do this, it could leave the possibility of Chronic Fatigue Syndrome, which is a diagnosis of elimination. It is still a very real illness and recognized by the Centers for Disease Control/U.S.-NIH.
I hope you find the answers and solutions soon!