I'd say that you have been under medicated for the past 5 years. Serum thyroid levels are the sum of both natural thyroid hormone from your gland, and thyroid medication. When you start taking thyroid medication, it changes the existing equilibrium among TSH, Free T4, and Free T3. TSH will drop, due to the med, and thus the output of natural thyroid hormone will also be diminished. The net output is essentially no change in serum levels. Only when the dosage is enough to suppress TSH will further increases start to raise your serum thyroid levels. So a doctor that tries to dose your thyroid med based on TSH doesn't really understand what is happening. Thyroid med dosage should ultimately be adjusted as needed to relieve symptoms, which is what you went to the doctor for.
In addition, doctors frequently just go by published tables for converting T4 dosage to NDT med like Armour. Those tables show that one grain of NDT is equivalent to 100 mcg of T4. Wrong. Even the ATA/AACE Guidelines for Hypothyroidism say that T3 is approx. 3 times as potent as T4. So one grain of NDT is equivalent to only 66 mcg of T4 (39 mcg of T4 and 9 mcg of T3 times 3 = 66). So your dosage actually went down from 50 to an equivalent of 33 mcg of T4, making your levels even worse than before.
A good thyroid doctor will treat a hypothyroid patient clinically, by adjusting Free T4 and Free T3 levels as needed to relieve symptoms, without being influenced by resultant TSH levels. Symptom relief should be all important, not just test results, and especially not resultant TSH levels. Again, many doctors don't understand this and think that a suppressed TSH when taking thyroid med means hyperthyroidism. That is incorrect, unless there are accompanying hyper symptoms due to excessive levels of Free T4 and Free T3. You can confirm all this by clicking on my name and then scroll down to my journal and read the one page overview of a paper on Diagnosis and Treatment of Hypothyroidism: A Patient's Perspective. At the bottom of the overview page there is a link to the full paper, should you want to read further. Also, a recent scientific paper by one of the authors of those papers concluded, "Hypothyroid symptom relief was associated with both a T4 dose giving TSH-suppression below the lower reference limit and FT3 elevated further into the upper half of its reference range." Obviously your levels are a long way from that, so you need a number of dose increases to get there and then some time for your body to heal.
I should also point out that hypothyroidism is not just inadequate serum thyroid hormone levels. Hypothyroidism is really inadequate T3 effect in tissues throughout the body, due to inadequate supply of, or response to, thyroid hormones. The response is affected by variables such as Vitamin D, cortisol and ferritin. So you should get cortisol tested to assure it is adequate. You should also get tested for Vitamin D, ferritin, and I would add B12 also, and then supplement as needed to optimize. D should be at least 50 ng/mL, ferritin should be at least 100, and B12 in the upper end of its range.
Your main obstacle will be to get your doctor on board with this. If need be, give him a copy of the overview and full paper and ask him to read and consider raising your Armour dosage to at least one grain now and then continue to raise until you meet the suggested conditions above and hypo symptoms are relieved. If he refuses then you need to find a good thyroid doctor that will do so. In that case, let us know and perhaps we can suggest a good thyroid doctor in your area, that has been recommended by other thyroid patients/