Hi MK,
Thyroid hormones do have an impact on the
menstrual cycle, so yes, it is possible that your missing
period is due to the change in medication. After my TT, my doc changed my Synthroid dose up by 12.5 mcg and my period went missing for nearly 3 months! Once my body adjusted to the new dose, everything else got back to normal as well.
If you are still concerned, it might be worth a call to your OB/Gyn just to check.