I would think it’s more about finding your particular fear/anxiety with the doctor than any blanket recommendation, but maybe a couple of things that might sound apt for you…
I take a list of questions to the doctor now, on a physical pad, and then jot down notes if I want to. It’s like an agenda for us to work off of collectively rather than relying on the doctor to cover everything from memory. They see dozens of people and each has their own style, and they’re not mind readers, so it helps me cover everything in one quick appointment rather than having to come back.
Not related to the doctor, but when I have a meeting I’m anxious about, I try to prepare well before (if possible) and then take something else to work on while waiting for the meeting. Basically once I’ve done my homework, rely on that and get your mind somewhere else. That way the anxiety can’t build, because you’re busy and doing something that doesn’t make you anxious. This would probably work well for the doctor’s office as well because many times you’re waiting more than you’re “doing” anything.
One last thing, I hope isn’t out of line, and is meant kindly. You’ve mentioned you don’t like not being in control, and the doctor’s office is definitely one of those situations where we’re all at the whims of others. Maybe finding ways to feel more in control, or a doctor who allows you to be more in control of your care, would help?