Thanks for contacting with your health concern 1. It is a common problem for women who have stopped taking depo injections since menstrual cycle irregularity is the biggest side effect, in some periods are delayed and in some heavy, irregular bleeding is there. PS. It may take up to a year for your cycle and fertility to return [after your last injection], seek a referral to a gynecologist. 2. other common causes which can delay regular period: - stress which disrupts the ovulation: causes your body to secrete more cortisol which delays or stops ovulation altogether causing irregular periods - Also, a diet low in fiber and high in saturated fats can cause irregular periods, likewise low thyroid [hypothyroidism] can also cause the same, so check with your Doctor. 3. check with home pregnancy test [HPT], since it can be upsetting and confusing when your period is late and there are no positive signs of pregnancy, so it could be due to certain lifestyle changes were done recently [if any] like: - excessive stress - loosing or putting too much of weight - heavy exercises - suffering from PCOD [polycystic ovarian disease] or having a high level of prolactin [hormone]