I saw a line on your first test, and not on your others.
It's possible you are experiencing a chemical pregnancy. If you want to know for sure you'll have to go in for a quantitative beta blood test (not qualitative which will just tell you yay or nay). Ask for the actual number and if it's high enough, they may have you repeat in 48 hours to see if you're rising or falling.
So sorry you've been stuck in limbo, I hope you're able to sort out an answer soon either way.