Unprotected sex, didn't ejaculate, day before period came as expected. 14, 28, and 36 days later, all negative hpts, still no period pregnant or late?

See below: If a correctly done pregnancy test is negative 36 days after the last episode of sex, you are not pregnant. Menstrual irregularities are not uncommon and anovulatory cycle is a common cause. If you miss more than two periods it would be time to see your doctor. Consult this site for more information on this topic. http://www.nichd.nih.gov/health/topics/menstruation/conditioninfo/Pages/causes.aspx