Was due to get my period last Thursday 24th & still nothing

Been overseas for 2 weeks & home for 1 week now. According to my cycle I was fertile during the first week overseas…in which time we had unprotected sex twice. 3 days after 2nd time, I had light bleeding, minor cramping & felt sick. Been feeling nausea since then on & off. Was due to get my period last Thursday 24th & still nothing. Taken clearblue pregnancy tests (3 of) & all were negative. Any ideas what this might be?

Age:22
Female
Medications: None

FIND THE BEST DOCTORS NEAR YOU

Cardiologists – Cosmetic Surgeons – Dermatologists – Ear, Nose and Throat Specialists – Gastroenterologists – Gynecologists/Obstetricians – Neurologists – Oncologists – Orthopedic surgeons – Pediatricians – Psychiatrists – Pulmonologists – Urologists