Some times I'm confused

Period never consistent. .One to two months it's 23 days then 24 days the other month then 26 days the next month y?

As a teenager it's was always 28 days which I loved. ..After becoming sexually active and being on birth control it stop. ..consistent was the pill. ..I'm not on the pill any more for about 2 and some years now. Don't have any intention of going back on it. .I was also wondering if it has anything to do with giving birth. .If that would change my cycle. Confused