Deprovera-Shot

Hi im a 32 yr old woman who had previously been on the deprovera shot after my 3rd son to prevent pregnancy, I`ve been on other birth control methods with major side effects such as uncontrolable bleeding,mood swings etc..The deprovera shot was working out pretty good other than the weight gain, I also got occasional bleeding approximatly once every 3 months when due for my shot, and I got migrane headaches. Now I am no longer on the shot it`s been a few months and I still haven`t started my period. How long does it usually take to menastrate normally.