Will I be 8 weeks or 6 weeks??

Hi everyone!

Not sure if this is the right place to post this, but I am confused as to what I should expect at my first ultrasound on March 8th. My last menstrual period was January 7th, but I know I ovulated on the 20th. According to my last menstrual period, I should be about 8 weeks at my first appointment, but should I expect the results from the OB GYN to say about 6 weeks? I know they count the two weeks prior to conception, but what should I expect the ultrasound to show?

Thank you!!