Depo vera contraceptive suppresses ovulation. It can also reduce menstrual bleeding and stop it completely. Delay in periods can be due to several other causes other than pregnancy. Stress, anxiety, too much of exercise, weight gain/loss all can cause irregular periods. Other causes of irregular periods are hormonal imbalances, thyroid dysfunction, ovulation disorders etc. A clinical examination and work up is very important for correct diagnosis and management of your condition. See a gynecologist. I hope it helps.
Best luck and regards!
I never had a period when on the shot. I thought that was the whole point of getting the shot...that and you only need it 4x per month. You may want to research something before injecting it into your body. It's quite common to not have periods with the Depo shot, dear.