Were you testing first thing in the morning with your first pee? So if this was the same pack with the same sensitivity and same time of day but 4 days later, I’m wondering if this could unfortunately be a chemical? That’s what happened to me when my lines got lighter a few days later. I hope that’s not the case for you.its just a case of either going to your doctor for a blood test or waiting a few days to see if anything happens. Unfortunately if you’re in the uk the blood test is unlikely,they will just tell you to wait
@Sarah I had the same thing and was desperate to see a darker line but mine were getting lighter on the super sensitive ones, but changed to negative on the clear blue. Blood test confirmed a chemical pregnancy but I've fallen pregnant the very next month and things are different this time. Stick with the same test type and brand for a proper feel of how things are progressing, and speak to your EPU. Best of luck!
How did you get on? Xx
I would maybe take a few different tests and ask the doctors for a blood test to confirm.