there are lots of variations of normal!
learning to keep track of your menstrual cycles is like learning a whole new language. first you have to learn about all the different parts (cervical fluid, basal body temperatures, cervix changes, & other secondary signals), and then you have to learn how it all fits together (how to identify ovulation, how to know when your period will begin, etc.).
just like there are regional dialects & accents, there is also a lot of variation from person to person. some people have longer luteal phases, some people bleed for different amounts of time, some people have cervical fluid for different amounts of time or different variations of the fluid itself.