What causes irregular periods?

Hi girls, i have a question
First of all ive been irregular my whole life and i was put on BC pills to regulate but i stopped few years back recently 6 months ago i started BC pills again because no periods :sleepy: well i stopped taking them once i was done w the package a month ago because my fiance and i are trying for our first baby. Has anyone gotten pregnant w irregular periods ? Or what can i do?