I stop taking pill last oct.3, i had my period last oct.7, i had sex with my bf last sept.19 and nov.1, now my period is delay.and my pt test is negative?

Other possible cause: Pregnancy is the most common cause of a missed period. Other causes of a late or missed period include: excessive weight loss or weight gain, increased exercising, emotional stress, having an illness, traveling, medicines (especially birth control pills), hormonal disorders, etc… can repeat pregnancy test in 2 weeks if no period. Seeing an ob-gyn doctor is a good idea if symptoms are recurring.