Faint line!

I'm posting this anonymously because I still don't know if I am pregnant. I took 3 tests today and two of them had two lines (Positive) and the other had just one(Negative). The ones that had two lines were very very faint. I'm going to test again tomorrow and Friday. My question is though, could I still be not pregnant or is there a pretty good chance I am cause the other tests? I have a daughter already but I found out from my doctor when I was pregnant with her. Never needed to test. Thanks!