my last intercourse was April 28th and my last period started the 7th of April and ended on the 14th, today is the 15th of May and i still have not started my period. on sunday the 13th of May i was having bad stomach cramping and i woke up that morning with yellow/orange pee i took a pregnancy test but it came back negative, and yesterday the 14th my breast started getting sore, could i be pregnant?