I am 21 years old, married, and my husband and I are practicing natural family planning. Because of this I am very aware of my cycle. My usual cycle length is 25-27 days. The last two months, however, my cycle has been 36 days. I have read that the normal menstrual cycle lasts up 28 days and cycles over 35 days are abnormal. What does this mean? Do I need to see a doctor?