Irregular after BC

Nicole
Hi my name is Nicole. I'm 33 and my DH is 31. TTC #1 for 2 months now. AF showed up this morning so im out this month. :-( Just got off bc 3 months ago and my cycles are now irregular. With them being this way I feel it's harder to tell when I'm actually ovulating. Any advice? Anyone know how long off bc it may take to be regular again?