Underactive thyroid ( Hypothyroidism
) can cause irregular/absent periods. But there are a number of other conditions which can cause this too. Do you have any nipple discharge
or headaches? Do you have excess hair growth on face, chin, abdomen, chest etc ? . You have not mentioned your age. What is the average age of menopause
in your family? A doctor need to examine you and suggest few tests. You may meet an endocrinologist
to evaluate further. ( if there are none available near to your place, please meet a gynecologist). Just taking medicines to bring back periods without looking for the cause is not a good choice. I understand your concern regarding having kids, but be assured that, most of these disorders can be effectively treated.