I have read many different things online for when ovulation occurs. is it 12-16 days after your period ends? 14 days before your next expected period?

Cycle days: The best way to figure it out without using ovulation prediction kits or basal body temperature graphs is to count your cycle days. A cycle is the number of days from start of one period to start of next (always count from first day, not last of period). If for example your cycle is 28 days, you likely ovulate day 14. 30 days would be day 15.

Mid cycle: Ovulation usually occurs 12 to 16 days after the first day of menstruation, so this is usually 14 days before the first day of your next, expected period.