you added something in your post about levels being off but not drastically
. let me try to explain something. First of all I'm not saying all your mental issues are or aren't caused by thyroid, I really don't feel in a position to commend on that.
As for your levels being off, normal (aka within ranges) does not mean much when it concerns thyroid. levels are optimal for a person or not, a comparison Midwest (thank you Midwest) makes and which i like is a shoesize, it's your shoesize or it is it, even if it's a normal shoesize does not mean it fits your foot.
That being said TSH is thyroid stimulating hormone produced by the pituitary gland and not an actual thyroid hormone It will rise when the actual thyroid hormone level (FT4 and FT3) are too low for the body's needs.
keeping in mind that a healthy person will have TSH around 1, AACE stated that TSH >2.5 is suspicious of hypoT, your TSH is too high for a person treated for hypoT.
TSH is not what causes symptoms, it's the actual thyroid levels which drop too low for the body's needs that will cause symptoms. within ranges does not mean much there, healthy people will have FT4 and FT3 around 60-80% of the ranges, at least midrange.
The symptoms and severity of those is quite an individual thing and don't always correlate with the extend levels are off. So yes one can have severe symptoms with levels which at first sight seem just a little off.