Hiii..its Been 10 And Half Month Of Our Marriage...i Hv

Hiii..its been 10 and half month of our marriage...i hv nt used by contraceptives but stil am nt pregnent...i had a check up and got to know that am having hypothyroid of 5.7 and having tyrox 25 tablet know...also they have given folsafe tablet to consume daily. .but this month I dint get periods its been 1 month 4days...usually I used to get periods early like 7 to 8 days before...I had pregnancy test but its negative ..y its so...is it because of having tablet my periods wil be late...its because of tablet or wr..plz confirm me ..