i don’t want to be pregnant

[i]hi i m 24, had unprotected sex with my boy friend on the first day of my periods. before tht i had 3 days before the onset of my periods i see only symptoms as frequent urination.is it too early to decide or predict if i m pregnant or how long wld it take.how cld i get to knw & whn?when is the the right time to get a pregnancy test done or hw cld i abort?it seems he ejaculated inside whn he had last, vagina was wet.pls help be going to get married to another guy in another 3 mths.cld not except all this!