How To Know When I'm Ovulating

Kayla
Hello friends. I recently came off the Depo Provera injection in July of this year. I have yet to spot, let alone have a full on period. We are trying to get pregnant but I am unsure of when I'm ovulating because I'm not regular. Has anyone been in this similar situation? What are some signs or tips to help inform me of ovulation?
 Thanks for the help!