Ovulation 2 days after AF?

So according to my calendar, I ovulated two days after AF left. If I go by calendar, I stopped ovulating 2 days ago and have never had cramps this bad in my entire life. But I truly don't know when I ovulate due to AF is here every 17 days. I have never had tests run to find out when I ovulate because it was never an issue. NOT TTC by the way.