Last period was around june 28, had unprotected sex on july 29 (no birth control) it is now august 17, still no period. no pregnancy symptoms as well?

Hmmm....: 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 home urine pregnancy test is very accurate 3 weeks after sex.