My date was 1 feb, i had unprotected sex at 18 of feb , next month on 1 march i hv my periods but flow was very light as if spotting , and i missed my periods this month i.e, 1 april  my periods are late i had taken the norethisteron tab 10 mg thrice a day for 3 day now its been 8 days and no sign of periods .  My periods cycle is 25 days and i have regular periods always. Also from past few days feeling sickness( nausea) . Is it irregular periods or pregnancy ??? Plsss reply