Help, me understand this fertility stuff

Charlene

If you don’t have regular periods. Example , skip a month. Do that mean you don’t ovulate the month it skip, or do it mean it just happens ovulation still occur and u just don’t loose the lining . I’m 21 days late. After negative test, I’m accepting the fact my cycle is just not regular. I don’t know 🤷🏾‍♀️if I can keep trying now or if my AF needs to come first