What do I go by?

Nicole • Baby girl 1/8/2020 💜, 2nd baby due Sept 2025 ❤️

By my LMP I’m 9 weeks 2 days but at my ultrasound they measured me 8 weeks 2 days & since it was a week difference they said they wouldn’t change it so do I go by my lmp or ultrasound? When I just called my doctor she asked how many weeks I was & before I said 8+2 she’s like oh your 9+2. Now I’m confused lol