Ovulation questions??

Hi All, i thought i had the ovulation thing understood and clear in my head, but after looking into it further i'm getting more and more confused.

So far i've been told the following:
1. count 14 days back from the first day of your last period to find out the day you ovulate.
2. Usually the 12th day of your cycle (or ther abouts) is your ovulation day.

If i wasn't taking my temp every day, which of the above (if any) would be the correct day to figure out my approx ovulation day?

I've done a calendar in fertilty friend and it gives me a totally different day. Answers, suggestions please. Thanks.

Edited by Shino266363 - 05 July 2021 at 8:30am