Pregnant And Confused?

I took a test tonight and there is a faint positive. (Pink dye test) im going to get more tomorrow but my last first day of my period I had put into a <a href="https://play.google.com/store/apps/details?id=com.glow.android.nurture">due date calculator</a> says I should be about 6 weeks. If so then why is my test line faint? Could I be earlier?