Thyroid and periods..

Hi,
I'm 25 years old, I have thyroid imbalance since 5 years.. my tsh levels are always high..more 6.0 .. My doc told me to take 50 mg eltroxin daily. my tsh levels go up down.. and 2-3 times i faced menstrual problems.. pain in lower abdomen and heavy periods of the 1st 2 days.. then 3 days normal. 5 day regular.. this is going on for 5 years.. but in times i would suffer heavy or very light periods.. but the period date would be perfect as only 2 or 3 days late or early..

Before 3 months ago i got my periods very late of 15 days.. my doc told me to check for thyroid levels and gve me meds for my periods.. i got my periods after 7 days of taking meds...

again for 3 months my periods were coming normal, and my period date is 30th of every month. now on 30 i had unprtd sex with my guy, but then i took I-pill, within 72 hrs.. and was safe.. but now its 15 days and i havent got my periods.. Is it my thyroids or something else? Am I hyper or Hypo? I have gained 25 kilos since 3 yearrs... Help please!!!!!!!!!!!!!!!!!!!!!