Background on this: June 13th I had unprotected sex June 14th I ovulated I was suppose to get my period June 28th -July 2nd never came prior to it me assuming it was coming I was cramping on and off, fatigue, and  nauseous I was 11 to 12 days late then on July 7th -15th I got my period was normal it was light brown, redish then medium red then back to light red. August 4-8th I was suppose to get my cycle just say I'm 12 to 13 days late I keep having cramps on and off, but nothing else and sore breast! I took a pregnancy test last night it came back negative I don't know what it is I don't know what it is I'm not stressed or anything! Nor has anything changed in my life I'm always normal and on time! Please help.