Lines seem to not get darker :(

i stopped birth control the end of november, had my first official period dec 24-29 2019.

since fertile week started i’ve been taking ovulation test- yet they seem to not be getting darker? i’ve been holding my pee for 4ish hours. taking the test between 12-8 & yet it’s been the same.

glow says it’s supposed to be my fertile week and i’m supposed to ovulate in 4 days. just getting a little discouraged and was wondering if any of you dealt with the same!