Should I be worried?

Since reading people comments on here I'm worried about the possibility of a false positive or a chemical pregnancy, does anyone else feel like this after reading comments on posts? Also how can people be so sure it's a evap line and not a positive? I look at a lot of the posts and think it's a positive but others say evap. Does anyone know the actual chances of a chemical pregnancy when testing early? It's got me really worried when I should be jumping for joy. I've done cheap tests that show nothing then today a first response which was positive and a boots own brand which was also positive. Should I be worried