Levels that doctors pronounce as "normal" are frequently inadequate to relieve symptoms because the ranges are too broad for the thyroid hormones. If you will post your thyroid test results and their reference ranges from the lab report, then members will be happy to help interpret if they are truly normal or could stand to be tweaked to relieve symptoms.
In my opinion as a patient Fibro is a medical "term" of inflammation and something is causing it. In Hashimoto's - the present of inflammation is fact and the body inflames with the autoimmune condition.
Fibro is a symptom of having this disease and when the thyroid levels are balanced correctly the Fibro disappears for many Hashi patients.