Toni Weschler is the author of Taking Charge of Your Fertility: The Definitive Guide to Natural Birth Control, Pregnancy Achievement and Reproductive Health, which is pretty much THE book for people who want to chart fertility, and the book I used to learn how to do it well in my 20's. She also wrote a great book about menstruation and charting for teen women, called Cycle Savvy: The Smart Teen's Guide to the Mysteries of Her Body. She's an amazingly dedicated and energetic person who also just happens to really, really like chocolate croissants.
It's a very tough thing to lose touch with your own body.
A little over a year ago, I started to feel under the weather. My joints swelled and ached, my stomach and guts were constantly cramping and gurgling, and my body was generally a wreck. My doctor brushed off these symptoms, chalking them up to things such as stress, allergies, and even gout. I began to lose weight, and suffer malnutrition as a side effect of my other gastronomical symptoms.