How many times you have sex in your fertile window?

I tryed to have sex in my fertile windows,but I have diferent apps on my phonw that say diferent dates ...So I never. Really know.Just want to know is that only me,or sex drive is going a little down and getting hrder to have sex that often,plus my hisband libido seams (always have been) to be very low.... i am 38 He is 41