Hello, well I am sure that having irregular periods are very confusing. And I suffer from irregular periods ever since the age of 16. I to have bleed for 25+ days, and my doc would give me Medroxyprogesterone for 3 wks to stop the bleeding. Do you have an underline problem? Like PCOS? Have they checked for cysts? Bloodwork to check hormones? Periods for some can take a couple of years in order to get regulated, while some just go right into coming like clockwork. I would see the docs and let them know that you are concern and if they maybe can put you on birthcontrol to start getting it regulated....or see if you have another underline problem that is causing your periods to not come. Best of luck to you.
Keep asking your doctor the questions until you feel satisfied with the answers. My daughter has 'unusual' gynecological problems, and she's had to try a variety of hormone therapies to get regular. Keep asking and trying new therapies until you find something that works. Good luck!