Up until my 40s my cycles varied 26 to 36 days regularly enough. My average remained 29.5 days (which is normal). I went to an acupuncturist (and herbalist) and it decreased the variance to 28 to 34 days (average remained 29.5 days). I don't know that there was an underlying issue for me. In retrospect there were reasons for most of the longer cycles - some stressor. Now my BFF and I are perimenopausal, so I am having 22(!)-26 day cycles and she is having 24-day cycles with "skip" cycles that are 40 days. I hope everything is ok with you.