STOP TESTING!
It's not an exact science all the tests will have a bit different amount of dye, that second frer could've been dodgy. Seriously you are doing yourself no favours and neither are people commenting saying they should be darker.. Why should they just cus yours were? No some people never get dark tests, with my first LO my tests were always light and here he is, and same with all my other pregnancys, one of the mcs I had the lines were really dark, it even says on the instructions it doesn't matter what strength the line is as long as it's there.