It's a simple fact that you won't get pregnant if you're not ovulating. The point which everyone believes to be true is that your ovulation is on every 14th day of your menstrual cycle isn't true. In fact, each person's ovulation period differs from one another depending on their menstrual cycle.  If you have irregular periods, then your ovulation period will differ. To know the correct time of ovulation, use various methods to calculate it precisely.