What Is The Treatment For Delay In Menstruation?

Hello, I am currently confused & worried. I am late on my period. My last menstrual period was March 24th, 2011. It is now April 30th, and I haven't gotten my period whatsoever. I've taken a home pregnancy test= negative I also took a urine test at the doctors office & it was negative as well. I have tender breast, get nascious from time to time & feel bloated. I've been developing cramping from time to time & my period is usually normal. I also been experiencing doing # 2 more often, which isn't normal for me and I also experience alot of gas, whats wrong with me? Please help. Thank you.