Cycle change 31d to 40d..why?

Samantha
When I was younger I had the worst periods! So irregular ! Some would be two weeks long some would be a month so I went on BC to control it when I was 15. At about 17 they became irregular again while on BC. So I switched. I did the pill the shot the patch. All made me bleed for a month. So I stopped taking birth control all together at 20yo (I'm 25). Since then my period was 31d cycle and my period last only 5 days very regular !!! This past year tho my cycles were getting longer and now they are 40 day cycles . I know there are factors and sometimes this just happens to women but I also noticed an increase in fatigue with this . I don't have my new insurance yet so I can't go to the doctor I was hoping someone can shed some sort of light on this matter. I don't want to have kids right now but I want to be able to in 3-5 years ya know? So anyone any advice would help I'm just hoping this doesn't screw with my fertility
Thank you
Sam