I Lost My Virginity Almost A Month Ago (24 Days

I lost my virginity almost a month ago (24 days ) . We had sex for like 10 SECONDS . We did it off and on for a few seconds for about 3 days spaced out . We didn't use a condom . BUT , he never came in me at all . It's been 3 weeks and I haven't had my period . I heard sex can throw your period off. My parents will kill me.. I don't have any prenanch symptoms like tender breasts or peeing a lot or nausea , but I feel this weird uncomfortable feeling in my stomach and lower area ? It does not hurt . I'm a little bloated also. I tried the homeade urine and bleach test about 6 times and it was negative . Help?