Irregular late period

Since I got my period for the first time it has been irregular , the first year I would get it for a week every 6 months or 5 . The next year it changed to every 3 or 4 months . It had gotten better , it started to skipped just a month or so . But lately it’s starting to get irregular again . I’m 16 and I’ve been told that the pill will make it regular but my dad won’t let me get on it . I need advice.