I have hypothyroidism and am being treated but I still miss my period. Is this thyroid or should I see a gyn? Not pregnant, and am on the pill.

See your Gyn! If you have been on the pill for a long time, it is not uncommon to stop getting periods. This can happen because the hormones in the pill can prevent the lining of your uterus from getting thick enough to bleed. However, pregnancy should always be ruled out. If your hypothyroidism is being treated, it should not affect your periods.
Depends. Could be your thyroid as well as other reasons as well.If yo continue missing your periods for 2-3 months you should see a gyn doc for further work-up.