Ovulation Help!?!

TTC #1, we have been trying for about 3 months so I decided to start using OPKs to more accurately predict my ovulation days. I have been taking OPKs twice a day (11:30am and 5:30pm) since CD7 and I am now on CD14 with no positives. This app had my original peak day yesterday. Is this normal? I've had a pretty regular 28 day cycle since going off of BC. Should I be worried? Am I doing the opk incorrectly? Any help from women who have done OPKs would be greatly appreciated.