I'm so confused

Jackie • 24 y/o Jake G 💍 mama to LNG 4/21/17 👶💙. SAHM . Idgaf about your opinion. It doesn't phase me🙌I say whats on my mind. Gtfo my page if your a hater. I don't need that type of drama. Stay blessed . 🙏🏻
So I was sent to get a measurements of Baby done. They had told me that the babies estimated weight through the ultrasound is 5 1/2-6 1/2 which sounds good to me. At the time I had this done I was 36w4d. They measured baby and said he's measuring 35w5d. 
36weeks is going by my LMP and 35weeks is going by AUA. So which one is really correct? I am so confused. Sorry if my is confusing too.