Glad to hear you are at last on medication and feeling better already but you need to keep a close eye yourself on your blood results by asking for copies every time you have your levels tested.
Also please ask your GP to test your vitd, b12, iron, ferritin and folates as these are often low in thyroid sufferers and if they are it will have a impact on how your body is able to use your levo.
Dont know if your GP has advised you that you need to keep your levo well away from all food and drink (except water) so that your body can absorb it. Levo needs an empty stomach to be able to absorb into the system, which is why a lot of thyroid sufferers take their levo last thing at night, having not eaten for a few hours before.
It seems that you have stuggled to get a diagnoses for quite a while but I'm pleased your now on the right road.