Whats wrong with me? last month my period was one day and this month its over a week late but got three negative pregnancy test results.

Irregular/ late: If you are not pregnant, other causes of missed/irregular periods 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.