am I pregnant

my last period was 3/1/12 I was suppose to start my nxt one on 3/29/12 but missed it around 2 or 3 weeks ago I took a cheap pregnancy test n got a negative so didnt worry about n still didnt get my period. im suppose to start my next period today but havent notice anything but I have been having alot of cramps today. and lately been having headaches and nauses. can I possibly be pregnant or is there something wrong with me

You need to test. Even if you weren't pregnant 2/3 wks ago you could be now.

The best time a positive will show up on a test would be after a missed period. I say test again, (First Response is a good, common brand to use on this site) and if you still get a negative, I suggest you see your doctor.