Hm, it is hard to say. My guess is that your thyroid is working slowly. But that is just a guess. Blood work at the doctor could determine that easily for you. It will also check your hormone levels and you can see if things are out of balance also contributing to this really long cycle. I had something similar in my 20's for about a year and a half. I got my period every 3 to 4 months. I had a combination of hypothyroidism and too much estrogen production contributing. A doctor can help you sort this out and that's where I'd head next. Good luck and please come back and let me know what happens, okay?