i really need to know if i’m pregnant

so i have had sex a couple times this cycle & my period is supposed to start today. he always wore a condom & never ejaculated inside of me. for the last three days or so, i’ve been having consistent back aches & cramps. my breasts were pretty sore a while back but nothing too out of the ordinary. i keep getting this panicky feeling but i’m not sure if i’m driving myself crazy with all this thinking or... i’m only fifteen & i feel so dumb for having sex in the first place. i really don’t want to ruin anything but i obviously need to know the truth so if you guys have any insight, that’d be amazing