I don't know why my period is late?

Periods often late: There's not always a firm answer for a late menstruation episode. The hormonal cycle that underlies menstrual repetition has connection within the brain (hypothalamus), and can be influenced by moods. Biologic reason: pregnancy occurs during stable times (e.g. Not during war). Certain "late periods" may in fact be spontaneous abortions, i.e. Pregnancies that are not viable.

Late period: Reasons for missed/late periods: low body weight, obesity, marked weight ^ or v, over-exercise, endurance athletics, breast-feeding, ^ stress, illness, eating disorders (bulimia or anorexia), anovulatory cycle (no egg released), travel, hormone irregularities, drug use, meds (i.e., birth control) or medical problems (i.e. PCOS). #1 reason is pregnancy.