I had sex with my partner 2 days before my period is supposed to come and my chance of getting pregnant was low.it's been 4 days late since my period isn't in.what is wrong with me?

Unsure: Did you have sex with him earlier in this cycle? Reasons for missed /late periods: low body weight, obesity, marked weight gain or loss, over-exercise such as in endurance athletes, breast-feeding, stress, illness, eating disorders (bulimia or anorexia), travel, hormone irregularities, drug use, medications (i.e., birth control) or med problem (polycystic ovary syndrome or Asherman’s syndrome. #1