Pregnancy testing

I dont trust the digitals a whole lot and they do usually require more HCG to trigger a positive. The line not being as dark as the control is no biggie. Sometimes you will never get a darker line and sometimes it wont get "dark" until well after 6 weeks pregnant. I would do another non digital test strip, they are pretty dang accurate. But it sounds to me like you are pregnant!

Could be you used a super sensitive test the firs time the others aren't as sensitive?

Keep testing. If it keeps getting lighter and more negatives than Positives, it’s likely a chemical.You could go to your doctor for a blood test.

Take them every two days to see a difference. Your urine could be diluted.