I haven't had a period since dec.24 it lasted four days my period is regular 28 day cycle its now February 3 and I still have know period I was cramping like it was coming the first week and my breast are very sore and my nipples are darker but no my back just hurts I took a pergo test and it came up negative can I be pregnant? i.e. my sister didn't read a positive test until she was four mnths pregnant

It's possible that it was just too early to test.

I'd wait another week. If you still don't get your period try another test. Make sure to follow the directions exactly. If it's still negative, I'd go to the doctor for a blood test.

Good luck.