I am so sorry for what you are going through.

I think the PP is right on with their reasoning for asking. It really surprises me that they did not have you see a doctor before setting anything up. I think, if it would make you feel better, you should call them and ask to see your OB directly, or at least for her to call you and speak with you on the phone. I will say that I generally do not see my OB at my ultrasound appointments - it is usually scheduled completely separately from my OB checkups. Is your OB familiar with your history? If they won't see you, I'd consider finding another OB who will give you the service and care you deserve.
Big, big hugs. I'm just so sorry.