Another question

Christine • 👧🏻4/2013 👦🏼11/2015 👼🏻 11/2019 🌈🎀 4/2021
So according to glow I'm 6 weeks 2 days. My ultrasound today measured out at exactly that. All the apps I use for pregnancy say my due date is 11/16/15 but the u/s tech said 11/20/15 so I'm confused lol