I think you could be on your way, but try to wait a bit before you test again. I would also say use the same test, not different ones each time. First Response picked mine up 6/7 days before period due and got darker every day without fail (using the same kind of test.) I don't think there is an exact science, but it seems to me that using the same test every time is a better way of testing when you're getting strange results.
I will say, though, that I swear by the First Response tests and they are the only ones that have been continually accurate for me and on your first picture, I saw the line. It's tricky to see but it's there. Mine was tricky to see to start with but as I say, it got clearer every day. Good luck!