How Long Does Lupride Causing Amenorrhea Take To Wear Off?

Hi,i had laprascopy in August last year to remove endometriosis legions. i was put on lupride soon after. i have so far had two 3 month shots in august and december respectively but my menses are not back. i last had them in september a few days after getting the shot and they were extremely painful. How long does lupride take to wear off?as I am on the 8th month without my menses and getting worried...am i still safe or do i need to use contraceptives??which ones do you recommend??