Rattlehead I don't convert T4 properly: there is no test as such for it: but for me I was upped to 500mg before a new Endo put me on T3: I improved so much after been put on it. My blood test results were a bit different: my T4 were normal: albeit very low normal, but my TSH was sky high.
Best thing I can reccomend to you is go to an Endo: and if they don't listen, find one who does listen. My endo is seeing me fortnightly at the moment because I'm thyrotoxic (pregnancy!!) and it really really makes a difference to have a good doctor "minding" you for want of a better word.
I feel the same way about Armour: some of the stuff I read scared me. But then loads of people have very positive experiences on it! I'm just glad the combination T3/T4 works for me.
Garhjw I would be very very slow not to take thyroid tablets even if you aren't displaying any symptoms. Like Cltt97 said if it is autoimmune long term the health complications would ge far worse. Even if you do decide not to take Eltroxin etc go for regular bloods and keep a really close eye on it. The other side is regular exercise etc is really good for anyone with thyroid problems so that may be why you aren't experiencing any problems.
Also if it is autoimmune in some people (like me!) the symptoms might not necessarily show up the way they do for most people: I have Graves Disease which is hyperthyroidism (before it was treated with radioactive iodine): and when I was first diagnosed I went from a size 10 to 18 in 5 months: the complete opposite of what you would expect.