I had my last depo shot February 12th, I just started to get my period back finally today. Now I…

I had my last depo shot February 12th, I just started to get my period back finally today. Now I feel like this is a dumb question but how do I know when I'm ovulating? I'm not a first time mom I have a daughter but I wasn't trying for a baby when I got pregnant with her. me and my fiance are trying but I'm just not sure :-/