im 3 weeks delayed and having some white discharge and crapms

i had depo inj last october2008 and im expecting to have my cycle this last week of january.. im 3 weeks delayed now and having some cramps..creamy discharge..ive red alot of Q and A about it..im so confused right now but i dont have any symptoms of pregnancy except for late period..
ive done a lot of pregnancy test it all came negative..
plesse help me...i dont know what to do..

am i pregnant?