First ultrasound!

Stacey • 27. Married💍BFP 20-7-16👶🏻 Baby Jacob Born 25-3-17
We have our first ultrasound this afternoon. Im so excited, nervous, anxious and everything in-between right now and it's only 7am! One of my concerns is this: going by my LMP, hospital say I'm 12 weeks. But going by my ovulation (I tested) I say I'm 9w6d. Will the doctor think my baby has stopped growing or looks too small if it appears as 9w? Or will they take my calculations into consideration too? Also, if I am only 9 weeks, will they book me in for a other scan in a few weeks to check progress and will I have the nuchal testing done?