I am wondering if I may be pregnant

My last period was February 26, 2005 and today it is April 7, 2005 and my period has not come on yet. I noticed that it did the same exact thing about two weeks ago. I have been a little stressed out but no more than usual. My nipples are very sore and tender and have been this way for about almost two weeks now. I seem to have menstrual cramps every day but my period still hasn’t come on. please help…………..