How do i know when i ovulated this cycle?

Use an OPK kit: If you have regular cycles use an ovulation predictor kit (opk) - test between 10 am and noon, starting on day 10 of your cycle. The first morning urine is not accurate. Try the ovuquick brand (available online, get the 9 stick pack) if a drugstore test doesn't work for you. The day of a positive test and the next 2 days are your most fertile days. If you have irregular cycles see a rei specialist.