Hi there i'm joules i am 18 i had unprotected sex on 9/13 but period was 2 days late prior ... also my period is now 13 days late and i took i pregnancy test came out negative i also started light bleeding with mild cramps but not sure if it's implantatio

Most often there is: not implantation bleeding - if it does occur - it is a very tiny amount of blood. 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 >