Some times it really helps to stop trying so hard. I've heard of many women who have gotten pregnant when they stop stressing and trying so hard to get pregnant.
Are you using an ovulation kit? Not all women ovulate in the middle of their cycles. You really can't go by a phone app or anything like that. It's best to use an ovulation kit. You might be surprised by thinking you're ovulating at a certain time of month only to find out it's a different time.
Good luck to you and your husband.