No doubt you have hypothyroidism but we need to find out the cause. Simple test to do so will be anti-TPO or FNAC from thyroid gland if enlarged. Thyroid scan is unlikely to give answers to your queries. Thyroid scan is useful for patients having thyrotoxicosis or multinodular goitre.In management of hypothyroidism, first step is to make TSH normal and after normal TSH if some symptoms persist then we need to find the cause by doing more tests. I suggest you to increase the dose of thyronorm to 50 a day and repeat TSH after 6 weeks. To avoid palpitation you may take thyronorm 2 hours after dinner as well. It is possible that you have other endocrine deficiency such as cortisol but this can be investigated only after TSH becomes normal.