Start of period was on 4/28. had sex on 5/15, but he did not ejaculate in me, and i am not experiencing any pregnancy symptoms, or any symptoms at all. my period still hasn't come yet. i have been stressed between 5/20-5/27. what could be the cause?

About late periods..: Pregnancy is the most common cause of a missed period. If not pregnant, 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… A visit to one’s Ob-Gyn doctor is a good idea if symptoms are persistent, recurring, or worrisome.