Help figuring out ovulation

Jennifer
New to glow. My names Jen. Im a stay at home spouse from Fl. I have af every 27-28 days for 3-4 days. Today's my last day (1/28 - 1/30) and was wondering if anyone is the same. And what day/s you ovulate. I use opks but hardly seem to catch it. And my temp never gets drastic. New here. Thanks all..