Anxious about ultrasound

I have my first ultrasound tomorrow.

I'll be exactly 8w according to my last period but I know I ovulated CD16. So I'll prob only measure 7w 5d.

I legit have the smallest bladder ... and she said I need to drink 4x 8oz of water finishing an hour before my appt. What if I have to go to the bathroom?

Is transvaginal usually what happens at this first appt?