PLEASE help me Am I pregnant?

I had sex Monday, unprotected. he pulled out, cumed, put his pants back on then we did it again about 15 minutes later. This week was my fertil window but monday was only the second day in so I didn't freak out, but I started cramping around my ovulation (I never have like that before). I became concerned and this morning I had heartburn, was gassy and cramping again. I took the Plan B pill This afternoon about 3:00 (3 and a half days since I had sex) I am still cramping and at the moment I feel slightly nauseous but not extremely bad. I'm just very concerned and would really like some feedback.