Frer lines

Do frer lines get super dark? At what HCG are they wayyy darker than the control line? I’m 6 weeks and took a test Monday and today and they seem to be the exact same. I would have thought the control line (right line) would be even lighter. It’s worrying me a bit so what’s everyone’s experience with this? I’ve seen where the control line (right line) is barely there so I thought mine between Monday and today would have been different. My lines have consistently gotten darker up until this week so it concerns me a bit. Top pic Monday and bottom pic today. Please let me know your experience!