Options for treatment of Toxic MNG are medications (you are already taking), surgery or radioiodine therapy. I suggest you to go for radioiodine therapy. As your gland seems to be not very large, surgery can be avoided easily. Other options are fine. Radioiodine therapy is very good option except that you have to wait for some time as you have a small baby and you might be lactating. By this therapy thyroid gland is destroyed by radioiodine. This modality is more suited for patients with toxic nodule or toxic MNG. Till you go for this therapy continue with the medications prescribed by your doctor.