B.C.
I had the same problems for a long time when I was on Synthroid.
My TSH would come back normal but I still had hypothyroid symptoms.
It got better when I switched to Armour Thyroid.
Synthroid is pure T4 and some people do not convert T4 to T3 which is the active form that your body needs to function.
Armour Thyroid contains both T4 and T3 and it made a world of difference for me.
When I talked with my Dr I told her all this time we'd been keeping me at the higher end of the normal TSH range. I wanted to try being kept at the lower end of the range. Normal is a broad range and the lower end is just as valid as the upper end. This helped me, too. I feel much better when I'm kept very close to almost hyperthyroid levels.
My Dr wanted to monitor me closely at first to make sure I was not getting heart palpitations and hyperthyroid symptoms, but I did great and have been feeling much better ever since then.
I was very fortunate that I have a doctor who was willing to work with me to find my optimum range. Not every doctor is willing to try, so you might have to find a new doctor if your current doctor will not work with you.