I think you should get a Full Thyroid Function Test - but if you are in the UK the doctor will not do it. I believe they've been told that TSH and T4 is sufficient.
It is good that you are feeling reasonably well but hair loss/dropping can be caused by hypothyroidism:-
Your doctor wont test all of the following but - if you wish there are private labs which will do them. They are home finger pin-prick blood draw. Blood should always be drawn at the earliest possible, fasting (you can drink water) and allow a gap of 24 hours between last dose of levo and test and take afterwards.
Doctor should test B12, Vit D, iron, ferritin and folate as deficiencies can also cause symptoms.
Always get a print-out of your results with the ranges. Ranges are important as labs differ and it makes it easier to respond.
Levothyroxine should be taken, usually first thing, on an empty stomach with one full glass of water and wait an hour before eating. If having a blood test 24 hours should elapse between your last dose and the test and take afterwards. It should also be a fasting blood test.
If B12, Vit D, iron, ferritin and folate are not tested ask for these too. Deficiencies can also cause symptoms.
If your hairline or density of hair hasn't changed much or at all in recent years, but you say your hair isn't getting better, what is wrong with it? I'm not sure what you mean by small hairs - are they the broken short ends of existing hairs, or do you mean fine new hairs that haven't attained full growth? It might indicate a number of things including inadequate thyroid hormones; inadequate nutrition through poor absorption or dieting, causing low levels of zinc, or iron etc; stress or other illness, inbalance of androgens - oestrogen is generally hair friendly, but testosterone less so, and too high a level of the latter can cause there to be a short hair life ie young hairs being lost too soon. And of course, it could be genetic - some males are predisposed to begin losing their hair in their 20's.
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