I agree (and I know from first hand experience from the past week!
A line is a line.
I tested on like sunday last week when I was only 7 DPO (no real reason, just thought I would), and I got a line like you are describing.

Hubby and I tested again on Wednesday night and got a darker line, but it was still faint, but definitely a line that time.

We tested today (AF is due tomorrow), and our line is now the same colour as the control.

Our very very faint is now a strong

With AF due tomorrow, and our line nice and strong, I'm feeling good.

I think your line will continue get darker!
Welcome to the world of Sounds like we are on almost the same cycle!