What Causes No Periods For A Year After Stopping Patogen Injection?

hello, im 28 i have never had children,am recently married and have been having injection contraception, Patogen,for the past 2 years, now 12 months after stopping using this injection, i still have not started menstruating, the nurse said the drug would stay in my system for about 3 months,but now its 12 months and i wana fall pregnant within the coming year, wat will happen to me??