My mensuration is late

dd

Its 45 days from day one of my menstruation and didnt come and i don BHCG on day 40 was negative i had unprotected sex 3 day ago and taked one emergency pill emediatly its been 3 day and no blood😔 iam stressed out i have exam and i have a baby 8 month old now 😬 what shal i do?!