any ladies due september 15

hey ladys quick question hope you ladies can help..ok so i got my first early scan a few days ago january 31 to be exact and baby measured 7 weeks the crl was 0.95cm does this sound normal..i didnt get my due date changed but doc said babys due date might be 18 or 19...acording to this if any of u ladies are around the same time as me when did we most likely conceived our babys my doc said most likely the last week of december do u ladies know when u conceived i mean i know you will never know the exact day but around when would it have been for us 😄