Positive test and question


So I just recently took a pregnancy test and it came up positive! Yay!! I immediately went to a <a href="https://play.google.com/store/apps/details?id=com.glow.android.nurture">pregnancy app</a> to start tracking my baby. It asked for my last period/conception date ( October 22. Last period. Conceived on November 5). It’s saying I’m 3 weeks and 3 days pregnant. How exactly is that? I’m 10 dpo today. Can someone please explain!?