you are on right medication. Ant the TSH
which has fallen down to normal now is because you are taking tablets. So not continuing the tablets means it will jump back to high TSH and you will suffer from the hypothyroid symptoms. The thyroid hormone is deficient in you and you should take supplements the way your doctor has suggested you to. This is life long. Now the level of TSH can be increased little bit by decreasing the dose by a few fractions. You should see your doctor for that. If your doctor has asked you to continue it then possibly he/she targets lower TSH in you- may be because you are planning for pregnancy
or so. So in my opinion your doctor has suggested you correctly.