is unlikely to make you miss the period but increases the chances of bleeding,same is with under active thyroid
2. Your treating physician has given you Hormone replacement therapy
to balance the hormone level, which is common around your age.
3. it is likely that you have attained menopause
and as a result your period got missed and co-existed with existing pathology.
4. Your Gynecologist is in better position to treat the condition, considering the factors associated at your age.