Pregnant, help?

my period usually comes around the 17th-the 23rd or 24th, but sometimes its late, because im still iregular[not too bad, just a few days, 2-3], well i had with my boyfriend a few times, but i've always stopped so he never came in me or anything [no condom] but i kno theres pre so i'm all paranoid. i know it was immature &stupid of me so don't lecture me please. but anyways, i haven't gotten my period yet [but there was only 28 days in february, obviously] so will it come later? cause it usually comes around the 17th, but it hasn't came yet. &it hasn't been like 28-30 days yet soo should i just wait til like the 25th and if i haven't gotten it yet, than go to the doctor or tak ea test. please help :/