I take a T4/T3 combo. I have had my entire thyroid removed - in two separate surgeries. The first due to a benign follicular adenoma where the discovered I had Hashimoto's but did not tell me (nice!) when I was 20, and the second, for colloid nodules and enlarged thyroid. I did not start thyroid until 15 years after the first surgery. I did not get T3 for almost 20 years. I myself cannot take synthroid as I got rashes from either the filler or the coloring so I prefer unithroid and have been very stable on it. I take cytomel as my T3. I need T3 as I have pituitary problems and do not convert well. Armour is great - but keep in mind it has a very high T3 component so you have to need that much.
What was your testing - TSH? Free T4, Free T4? The frees really tell what they thyroid is doing - the TSH just says what the pit is telling the thyroid. Why that is the gold standard, no idea because they don't test if the pit is healthy so it can be one unhealthy gland talking to another unhealthy gland.