pregnant. ?

I was supposed to have my period on the 27 but I didn't get it , every month I would get my period on the 21 but this month I didn't get my period at all . I had sex on the time I was ovulating & he cummed inside of me . I took a test on the 28 & negative it was 2 weeks-after the  unprotected   sex  . Idk if it was too soon but my boobs are really sore they've been sore for  a week  Can I be pregnant or ? When should I test again ?