Colour of BFP

Hello, I took a hpt yesterday at 13dpo and it was positive, today I took another and it’s slightly fainter then yesterday. I have had a chemical before so I am convinced I am having another chemical. Should my tests be darker then this for 13/14 dpo. My internet cheaper is vvvvvvvvf as in I can only see it when I shine a light.

I am 4weeks 3 days going by last period. Also is there any other reasons why test can be fainter the next day? I didn’t drink before hand and was FMU. Any advice would be great :)