If the dates you are trying to distinguish between are somewhat close together, the best way to try to tell is to get an ultrasound, the earlier the better for accuracy in dating.
If u have a smartphone there is an ovulation app
I have not had an ultrasound , unfortunately . my family physician estimated a due date of December 10 based on my lmp .
Have you had an ultrasound? Your best bet for identifying your ovulation date is to get an ultrasound in your 7th or 8th week, then plug the estimated due date into a conception calculator. Your lmp will not be as significant (unless it matches) as the measurement given by the crown-to-rump size of the embryo.