How can you get pregnant when you're not ovulating?
Normally a women ovulates one time during her monthly cycle. When a women ovulate she releases on egg from her ovary. That egg waits in the fallopian tube for 18-24 to get fertilized by a sperm before it is no longer viable.
Sperm can live in a women's body for up to about 5 days. So having sex before you ovulate is important for trying to conceive. When trying to conceive you always want some sperm in there waiting for the egg to be released.
So even when you are not ovulating you can be prepared for the egg. If you do not ovulate you can not get pregnant. Ovulation is required to get pregnant.