okay, i'm only 17, so this is very scary for me, and it could just be because my period is not regular yet, but it has never been this late (5 days today) and i haven't had sex since my last period, or what i thought was my period, it happened 12 days after i had sex, 3 days before my period would normally start, i had cramps, moodiness, and it was normal amounts of blood for a period (light to heavy to light) and lasted about 6 days. I have just got out of school, so my sleeping pattern has changed a lot (during school i would go to bed around 10 and wake up at 7) now i'm going to bed around 1 or 2 and sleeping til 12 or later, and since summer has started i have gained some weight, about 5 lbs, and today, 5 days after my period should have started i feel crampy, i have NO other symptoms of pregnancy, i dont feel sick when i wake up, my boobs are sore or tender, the only symptom i have is a missed period... what do you think is up?

[moderator note: i split this post from an old post that the user bumped up. please create a new topic if you wish to ask for advice. thank you]