Brief Answer:
As explained below

Detailed Answer:
Hello,

Thanks for posting your query.
As you are taking thyronorm I would suggest you to check the levels of tsh, t3, t4 levels. You may require to alter the dose accordingly.
Any changes in weight can also cause irreguler periods, do try to maintain your bmi.
Regular exercise. Walking and deep breathing exercises can also help regularise your periods.
If it still does not help it is best to visit a gynaecologist and start medicines for the same.

I hope this helps. Please feel free to discuss further if any.
Regards.

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