Progressively darker HPT's

Jasmine • 21 and in love with my babies ❤️
Okay, so I'm not able to get in the doctor until jan 7 to get a blood test. Today marks the 3rd day after my missed period. The top one is from Christmas Day. And the bottom one is from this morning. So here's my question...does pregnancy tests get darker when there's more hcg present? I just want to make sure everything is fine. (Wish I could go to the doctor earlier to ease my mind).. thank you for your responses :) (not stressing though, I know that's not good)