The shot

I am 20 years old and in college. I have been using the shot for about 3 years despite the recommended two due to my doctor.due to the shot I haven't had a period in 3 years. Because of the side effects and what it was doing to my body I have decided to quit receiving the shot. I've been off it for almost a month and I still haven't gotten my period. How long does it take for my period to return?! I've got all the symptoms but they are only temporary:/ help!!