My Period Is 27 Days Late / Not Pregnant Not Trying I Just Want My Period To Be Normal

So My Period Was Suppose To Come Today , But It’s Late By 27 Days. Ive Went Months Without My Period & It Worry’s Me I Possibly Couldn’t Have Kids In The Future . My Period Always Been Irregular. How Can I Regulate My Period So It Can Be Normal ? I Need Some Advice. And No I’m Not Pregnant , I Don’t Want Any Kids Rn.