My mp started today 2/1 but prior to that my lmp was 12/24. what could be the reason for the delay/skip of periods?

Delayed menses.: 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. #1 reason is pregnancy.

Irregular cycles: Delayed or no ovulation is the cause of irregular cycles. See your gynse.