Confusion about OPK

Hello,

We are ttc #3. I am still breastfeeding my 1 year old. My cycles are approximately 26-30 days long. But are becoming more regular around 26 days. Question: I started checking my surge on cycle day 8. I am using the Wondfo opk strips. On day 8 I saw a faint line. However, each day after for the last couple days there is no line. I'm confused. Wouldn't the line continue to darken as ovulation gets closer? Just curious if anyone else has experienced this? Also, I was using Progessence Plus daily just to boost my progesterone levels. Well I have ceased doing that after hearing using progesterone prior to ovulation can suppress it.

Thanks and best wishes to you all!