Vfl for days, is this normal?

I’m currently 11dpo, I’ve taken pregnancy tests for the past 5 days. I know I started early and I shouldn’t be taking them every day, but I’ve been too impatient 😬. There is definitely a very faint line, but it hasn’t gotten any darker over the days. i read the HCG should be doubling every 2-3 days but it doesn’t look like mine is. Is this concerning? Should it be getting darker by now? AF is due in 2 days. Anyone have any thoughts? any feedback would be great!