I just took a pregnancy test a couple days ago and it read positive so I downloaded two different apps to track my pregnancy: BabyCenter and text4baby. My EDD is Feb 24, 2018 (based off of my own calculations) BabyCenter says I'm 7 weeks pregnant and text4baby says I'm 8 weeks. Any reason why that might be? My first appointment is next week so I won't have confirmation until then but I'm curious.