Positive tests late?

Tara

According to my period tracker, I supposedly ovulated on April 6. I took a test 12 Dpo 4/18 and 15 Dpo 4/21 both were negative. Period was due 4/19. I didn’t get a positive til 18 DPO. 4/25.

Has this happened to anyone else? Not getting a positive til so late? Or do you think I ovulated later? So confused. Can’t wait til my appt on may 9th