Kate, I am so sorry you had such an experience with this doctor. First of all, I think you handled it very well. Second, I think how you act (not react) now will make all the difference. Third, you do not need to let this woman who is on a power trip and tried to control you, win. You need to write her, in a very professional way that you two seem to have a personailty conflict. That she obviously views you as someone who is unable to make her own choices. Perhaps you agree there are things that have gone unfinished in your life when you were a teen-ager but as a woman you will make the choices that are right for you, the first being getting your health under control. You have that right as an adult, and you are exercising that right. Then tell her you are seeking help elsewhere with a doctor that is better suited to your positive approach.
This way you have it in writing that you believe she has a problem in so many words and it has to be in your file. The run, don't walk to another doctor!
I am just telling you what I would do. I once took my son to a doctor because I loved him very much but we were having problems getting along. He was 15, 180 lbs. She tells me when he is out of line stand him against the wall for time out. I said are you serious? I would never insult him that way. I am asking him to behave like and adult and I will treat him as an adult. My file read, mother will not cooperate with treatment, little hope for son. I wanted to cooperate my foot up her backside! Good luck to you!
By the way, son is now 23 and doing great and he loves his Momma very much!