I had head pressure, brain fog, PEM, dry mouth, dry eyes, muscles problems, etc.
My head pressure resolved after I started taking T3.
My muscles and PEM problems need more than that to stabilize, I use prednisolone and caffeine.
No endocrino would have diagnosed me with a lack of hormons, as they are all in the normal ranges, but I can function with them.
So yes I agree with the lazy doctors.
TSH is not a marker of thyroid activity, it's only a marker of pituitary activity, so you can be hypothyroid with perfect TSH if you have a hypothalamus/pituitary axis problem.
fT3 and fT4 are not good markers as well because normal ranges include hypothyroid patients as "normal patients", and also needs can vary from one people to another. Etc...
Good doctors will treat you according to your symptoms, not your blood tests only, but they will do it outside of the medical consensus, which can be dangerous for them.
In my country, not any doctor will take such a risk.
Some evidences can show you are lacking T3 (I have both):
-low blood DHEA or pregnenolone
-hypercarotenemia