i was always told 13,14,15,16 days after your first day of period ...ttc 5 years never used an OV kit until 2 months ago ...boy i was wrong first time my RE told me to use it my first OV day was 9 days after my period
I also been using preseed to
I been doing opks for the last 3 days and it's positive today
Yes. A calendar can't always help predict your ovulation and sometimes you may ovulate later than you expected, earlier than you expected or not at all for the month. The only way to tell somewhat is to buy ovulation predictor tests. They are used like pregnancy tests. You pee on them and if they come up with a smiley face you are in your fertile window.
Another way is to become VERY in tune with your body and the signs and symptoms of ovulation, cervical position etc. Good luck