faint lines on pregnancy tests but 21 days late.

Charlotte
I'm so confused right now, I have been testing since I was 2 weeks late as my cycle is normally 34-36 days, I'm now on cycle day 50 and all my pregnancy tests are really faint lines like you can't really see much, I took a clear blue one yesterday morning and it come up with a faint positive line within 20 seconds so it couldn't be an evap line but now it's just dried it's so faint you can just about see it. I've got no sign of coming on, I had bad cramps last night but apart from that I've had nothing.
Has anyone else experienced this? Or going this is and got a clear BFP