Based on your symptoms there’s no way you just have low T, likely thyroid issues as well. You should be checking TSH, fT3, rT3, fT4 and antibodies, anything less and you won’t have a clear picture of what’s going on. fT3 is where the rubber meets the road, this is the only active thyroid hormone which acts on thyroid receptors.
Most doctors you have to fight with to run fT3 labs, you should order these through discount labs so when you go see a doctor the discussion is more productive and action can be taken right then and there. You’re estrogen dominant and you will require arimidex once you start TRT or else you will suffer greatly.
Most insurance doctors will refuse AI’s so you may need to go private, reason is guidelines don’t mention anything regarding estrogen management or even running estrogen labs. What are your morning and afternoon body temperatures using a glass thermometer? Most salt doesn’t contain iodine, you must specifically get salt that includes iodine. Sea salt has no iodine. See thyroid sticky.
You need more labs to determine why testosterone is low, prolactin and estrogen can cause gyno. High prolactin can lower LH and therefore lower testosterone. Everyone responds to TRT differently, some within hours (rare) and other’s weeks or months and some a year. It will take longer if dealing with incompetent doctors, that describes myself.
Very few doctors would even give a 21 year old TRT without first trying Clomid, which raises LH and in turn raises testosterone.