Faint positives

Hello, has anyone had their tests get fainter. Seeing the line fade has really upset me and I am fearing the worst. I have gone to the doctors for a blood test today which I was booked in for anyway as it is the first blood test since finding out I was pregnant on the weekend. I am 4 weeks 5 days. Has anyone has a similar situation and if so what happened? Chemical maybe? Or could the pregnancy be ok?

All tests in the pic have been done using FMU.