Fibromyliga "showed up" just AFTER the TSH test was adopted as the gold standard test for Thyroid function.
TSH nearly a worthless test. Yet it is used in many cases as the ONLY test to be done and the only thing Dr's want to look at. The problem is that it is a screening test at best.
Isn't it funny that when "they" started using the TSH test as the gold standard (instead of in combination with clinical symptoms), all of a sudden patients were having all these "unexplained" symptoms. And low and behold most of these "unexplained" symptoms are consistent with Hypo. yet because the TSH test says they are normal or perfect, the symptoms then are "unexplained" because they do not believe it is due to low thyroid.
Now the medical field is finding that when fibro patients are given thyroid medication, their symptoms are lessened or eliminated completely.
It is my opinion that most of all Fibro is simply undiagnosed Hypo.
Just my opinion, but shared by many.
Your thyroid labs really look good. Your FT4 is a little low, but that's not unusual when on desiccated. You could try adding a little synthetic T4 to your Erfa to try to get it closer to 50% of range.
Ferritin has to be around 70 so that thyroid hormones are properly metabolized. You should also have vitamin D and B-12 levels tested. Both of those can cause fatigue, B-12 especially. Once again, D must be well up into range for thyroid hormones to be able to get into cells. Just being in the low end of range for D and B-12 is not good enough.
The only comment I can make is that you may do better of on a T4 only product. I had similar issues to yours on erfa and did not respond until I switched to synthetic T4. I had lots of muscle symptoms you could call "fibromyalgia", but I told my MD I'm not taking that for a diagnosis as I believe it is a catch all. What were your labs before you started to take erfa? If your T3 was already at a good level you may only need T4. Based on the labs you provided it appears you do need some more T4.