I just don't get it..

Been married 4 years, and for 3 years I have been following my "fertile window" no tracking, not anything, just baby dancing through my fertile window whenever we're in the mood. Finally got pregnant this past feb, unfortunately I MC. So now that we've talked and discussed wanting a family, we're ready. So now for 4 months I've been tracking with opks. My cycles are very regular and on point, always has been. I'm healthy and my husband sperm has no issue. I don't understand what I'm doing wrong? I bd before I ovulate, we bd on ovulation day. What is it? Kills me cause I just want to start a family and bless my family with this baby. Any feedback would be appreciated. Anyone dealing with the same thing?