When will period return?

I have had migraines for the past 7 years, so my dr decided they may be caused by estrogen in my pills, but sent me for CT scan, just in case. Well everything was fine with head, so she swapped me from bc pills to the depo provera shot. I have not had another migraine, but I had the shot in april and didn't get another in july because my husband had a vasectomy and he was sterile. I have not had a period since I got the shot and was wondering when it will return. I don't like not having a period, I think we have those for a reason and I want it back ha.