Can I be pregnant?

My predicted fertile dates were from the 2nd-7th of July.. The 6th being my ovulation day. My boyfriend and I had sex on the 2nd and the 4th and both times he came inside me. My period is supposed to come on the 21st of July.. I've been having nausea all day for the past 3 days and I am cramping along with breast tenderness (on the side of my breast).. Is that signs of pregnancy? Or maybe just my period?