I haven't used a CBFM for years, so don't know if I'm remembering this right, but have you used it for quite a few months? I'm thinking that if you've used it for awhile, it's gotten to know your cycle well enough that it knows more exactly when you peak and doesn't need additional days to make sure (like the typical low - high - high - peak - high, etc.).
Enjoy the little things, for one day you may look back and realize they were big things. -- Robert Brault
"We either make ourselves miserable,
or we make ourselves strong.
The amount of work is the same."
"The will of God will never take you where the Grace of God will not protect you."