I am 21 years old on the 5 th of this month i had sex with my boyfriend for first time, on the 7 th I had started bleeding but only for a few hours then nothing. I usually have 3-4 day periods. My friend said it was probibly just from having sex for first time... But now it's been 15 days and I still nothing, shouldnt i have have had a period... We used condom but not When we first started.. can u get pregnate from pre cum... oh and I have the same old cramping lower back pain, mood swings as I do when I am on period just no blood... What could be wrong with me...?