Is it possible??

So I’ve been testing for ovulation for about 3 months now and decided to try this month to get pregnant. I’m one of those that can sometimes feel that achy feeling and just know I’m ovulating and I’ve been right these last 3 months when I test! I’m trying to conceive right before I ovulate in hopes to see if we can get a girl (Read up and been told to have sex before your actual ovulation day to try for a girl) so my question is...if tested a week before this app says I’m ovulating, could I have missed it if I didn’t eat everyday because I had darkish lines and just last night it was lighter than the previous ones! Could I have ovulated earlier than usual?! 😬🤷🏼‍♀️