14dpiui BFN

Judi
14dpiui and BFN 😟 I used opk this time. Can opk be wrong? Does this mean I did IUI on wrong day? Anyone got bfp after getting BFN on 14dpiui ? AF has not shown yet and no sign of it.
With ultrasound I had IUI on day 17 and with opk on day 15. Should I wait two more days for AF?