My last period was august 22nd. and i have no signs of pregnancy besides sore breasts. and negative at home tests. what could it be?

See your doctor: There are a number of conditions that can lead to amenorrhea, which is the medical term for no menstruation. You should see your physician to figure out why you haven't had a period. Good luck!

Are you late?: Reasons for missed / late period include: an anovulatory cycle in which no egg is released, marked v or ^ in weight; eating disorder; Over-exercising (endurance athletics), stress, travel, significant illnesses, oral contraceptives & other meds, Illegal drug use, breast feeding, hormone imbalances and medical problems (i.e., PCOS). Pregnancy is #1 reason.