period for 55 days

me and my boyfriend have been ttc but with no luck. I was on the depo shot for a year and got off of it last May and didn't start having periods till around September and now they just all over the place. I'll have a period every other week sometimes but this last time I was on it for 55 days and no one understand why. I'm still trying to figure it out myself. But yesterday I finally started my period after a month free of bleeding. what signs should I be looking for in order to tell if I'm ovulating. I want to have a baby so bad. I'm fixing to be 26 and have already a baby 5 years ago and I'm ready to be a mommy again. any help or advice will work. Thank you