Frustrated with estimations, Anyone else?

I understand they’re just estimations for ovulation/period. Have been actively tracking my ovulation/periods on glow, currently have 2 girls, July ‘15 a Nov ‘17 baby. I can totally tell I ovulated earlier than what glow estimates. But when I put in the pertinent info, it doesn’t change the estimation much. Have had close to positive opk’s, which have then faded (ovulated between testing?), also had a SHOW cervix and heavy egg white mucous. My husband and I are not using protection, but are open to whatever happens. Just ranting I guess...