Getting Darker??

Kayleigh
Can anyone tell me if these are getting any darker?? I can tell that the first one on 12/28 is significantly lighter than the rest...but after that I feel like they aren't getting darker as fast as they should and I'm getting nervous :/ the first one on 12/28 was taken 11dpo, the 29th 12dpo, 30th 13dpo, 31st 14dpo, and the last today, 1/1, 15dpo.