OP here. I know, right? I mean, I was all set to go in today and talk about how great DD was doing. We rarely ever see a tantrum at home or even when things go wrong out and about – huge lines at the grocery store, what have you. She's generally pretty easygoing unless something really sets off alarm bells to her. Even then, she is often able to self-regulate, usually when she sees the threat is temporary (the shot is over, time to go home).
Actually the doctor is a she and has three kids of her own, including one with ADD and one with anxiety. You'd think she wouldn't be quite so judgmental.

I actually tried to intervene several times – told the nurse to bail on the blood pressure thing, told the doctor several updates about her speech delay and what her teachers thought. I also tried suggesting, when DD was obviously quite distraught, that perhaps she could do the exam with her clothes on. Doctor said no, and then told me I needed to be firm with DD about what happens when we come to the doctor. Sooooo....not really feeling it with the doctor today. I can see her point of view, but as you say, my DD gets anxious and a little bit of understanding would have gone a long way.
Given that my other two could also be anxious, I considered CBT for her, but because of the speech delay, I feel she would need to be a little more articulate to be able to have it have an effect. The doctor said not much could be done for anxiety at such a young age – she sees it a lot with potty training, for example, and said mostly you just wait it out. We do a lot of role-playing at home for things that might be coming up that are scary, but I'm open to suggestions.