When I had this problem (undetectable TSH, normal T3 & T4, hyper symptoms) my first endo said I was basically crazy and that my symptoms were not related to my thyroid.
I got a second opinion and they said the symptoms WERE related and I had an uptake test done (I had already been treated with RAI in the past). The uptake proved I had a reoccurance of Graves, even though my T3 and T4 were “normal”.
Maybe a second opinion wouldn’t be a bad idea.
Patrick S