Glow wrong on how far along I am?

Lindsey
I just downloaded glow <a href="https://play.google.com/store/apps/details?id=com.glow.android.nurture">nurture</a> because I just had my first BFP this morning! The digital test said 1-2 weeks which makes sense because I ovulated exactly 2 weeks ago. But the app says 3 weeks 5 days? I don't get it.