I'm not menstrating either and have begun charting about 2 weeks ago. I take my temp, CP & check CM. Though I'm not breastfeeding so I'm not sure how that would affect temps etc. My LMP was 3 months ago so I have put that into FF to start the cycle. I guess you could just put in any date as the start of the cycle. I would put in a date around 6 weeks ago, but just start temping etc from now. Unfortunately I can't say how BF will affect your chart, as I don't know. I'm sure someone will answer that one. Good luck with it