Period 20 days long?

Ok hi well leme give you a back story first.

I'm 14. Ive had my period for 2 years. I'm not regular yet. Just this past summer I started to be. When I have my period it is for about 7-8 days very heavy and terrible pains. I got my period august 18-21.

Then I got it September 18. September 19 it stopped then September 20 it started again. It gas been non stop bleeding since then and it is currently October 9th. Witch makes that 20 days.

Does any one know why this is happening? Its insanely frustrating and hurts a lot. Please help! Thank you