DOES YOUR BODY GET IMMUNED TO THE SHOT?

I HAVE A QUESTION AND MAYBE SOMEONE ELSE HAS EXPERIENCED THIS AND HAS AN ANSWER? I HAVE BEEN GETTING THE DEPROVERA SHOT FOR 7 YEARS. I DID HOWEVER GO OFF THE SHOT FOR 1 YEAR. I LOVED THE SHOT BECAUSE I DID NOT HAVE TO THINK ABOUT BIRTH CONTROL EVERYDAY AND THE BEST PART WAS THAT I NEVER GOT A PERIOD. HOWEVER, FOR THE PAST YEAR I HAVE BEEN GETTING PERIODS. NOT JUST A TYPICAL PERIOD, RATHER A HEAVY, BLOOD CLOTTING MESS. IT LAST FROM 5 TO 7 DAYS. MY QUESTION IS BECAUSE I AM NOW BLEEDING, DOES THAT MEAN THAT I AM IMMUNED TO THE SHOT AND THAT I COULD POSSIBLY GET PREGNANT? SHOULD OR DOES ANYONE RECOMEND THAT I SWITCH BIRTH CONTROL MEATHODS? MAYBE TRY THE PILL? ANY ANSWERS WOULD BE ABSOLUTLY APPRECIATED. THANK YOU

AGE 30 YEARS OLD