If you don't release an egg (ovulate), you can't get pregnant - there is nothing to fertilize.
Remember that although period length may differ from woman to woman, it is always 14 days from date of ovulation
to period in any month the woman doesn't get pregnant. Also remember that sperm
will will wait for an egg (up to 72 hrs), but the egg won't wait for the sperm (gone in 24 hrs at best).