Furyan, me too. I have stopped face to face work and now work online from home only, partly due to this.
You might find the Mirena effects wear off. I seem to remember that for a few months after it is fitted, it does release a bit more progestin which can go systemic. But then it reduces to the regular dosage and it stops going systemic for most women.
The only reason I sometimes doubt the estrogen-thyroid thing being a cause for me, is that my thyroid panel was actually pretty normal before I ever went on thyroid meds (even after starting HRT and after these symptoms had begun). I had high rt3 (33, above range) and low but in range T3 (3.9, range 3.2-6.

. We were a bit sceptical that this would be enough to cause the symptoms I was experiencing so it was a 'trial treatment' to give me a bit of T3 and see if it had any effect.
I really now suspect that if I had never gone on thyroid meds but just increased my estrogen sooner into the 850pmol ish range, my symptoms would have gone away. And that I really just needed this higher E dose.
The reason we didn't try that earlier, is that at first I appeared to be incredibly sensitive to estrogen: This all began when I started estrogen, even on a low dose of 50mcg and it at first appeared to get worse (not better) with each dose increase. So I stopped it totally for 6 months. So due to all that history, the decision to trial higher doses was very delayed. And by then I had begun thyroid meds.....
And for some reason starting the thyroid meds caused my own pituitary to give up so that even when I came off them, I never recovered previous function and had very low T3 and T4. So now I really do have a bone fide thyroid issue as well. However, I am doing well at the moment: I've managed to source some Estradots again from Newson and CLoudRX and I've just increased my T4 and am sleeping well.
At the moment I am a sink for T4. I am increasing doses but levels are not going up on bloods, I feel great for a week after increasing and then it backslides. Just increased to 125mcg T4 and still on 30mcg T3. Waiting for this endo referral...