I have just finished my first cycle of charting and using FF. Even before this, I had guessed that I ovulate around Day 18 (sometimes get cramps). After putting in my BBT and CM info for the last month, FF agreed with me. Was a pretty easy to interpret chart. FF drew the cover line and marked Day 18 as my ovulation day for next month. All good.
AF arrived on Friday and I put this into FF (therefore marking Friday as Day 1 of my new cycle). It then took it upon itself to change my upcoming ovulation day to Day 12. This is definitely not right. I have a short luteal phase and it's almost as if FF is telling me closer to what my ideal ovulation date would be, rather than my actual one!
Ultimately, it doesn't really matter because I know what the real date is, but was just wondering why it might have done this? Does it perhaps take a few cycles for it to get the message that yes, I do have a short luteal phase and that wasn't just a blip?