I think the reason your TSH drops low is because you were using fast acting
Cytomel. After you take it, you get a blood level spike of T3
for several hours and that high spike is what lowers your TSH. Personally I am using compounded slow release T3, which supposedly releases the T3 over 12 hours, so your blood T3 level does not spike nearly as high. For comparison, my TSH on 100 T4 + 5 T3 was 2.29, and on 100 T4 + 15 T3 was 1.52.
Armour comes in 1/4 grain (15 mg) sizes.