Late ovulation anyone?

C • TTC #1 since July 2013, BFP 14.11.15
So I've always believed I ovulated day 14 ish due to a 28 or 29 day cycle. After 2 years and different fertility treatments, I've started the clearblue digital ovulation kit. So it's day 15.... Nothing. I'm getting a bit concerned now... Has anyone had experience of late ovulation with normal length cycles?