These tests are renowned for having fainter lines i would try a different brand
What time are you leaving between tests? Hcg doubles every 48 hours so you should leave it this long between tests to be able to see a difference. Also, it’s not accurate to compare a test that’s been drying for a while to a new one, so the best way is to take a new photo of each test when it’s developed, and then compare the pictures x
When were these all taken from one another , HCG doubled every 48hrs