Glow windows

Good morning to all my beautiful mamas and mamas to be. First of all baby dust to everyone ttc. Speaking of that I am ttc. I was wondering on this app when it says your next period is 18 days away and there is an 11% chance fertility but the daily log says different after entering cervix position an cm is light and watery is said 75% fertility. I don't want to so the ovulation test and that stuff but was wondering what the percentage ment . It says my most firtal day will be on Sat the 19 with a 33% chance. . Dose that mean that until that day It's kinda a hit or miss or how do I know.

Thank you for your responses.