Poor Dr. Au. I say that without any sarcasm at all (rare for me, I know), because she's on the horns of a dilemma: freeze to death in the OR, or be taken for an RN?
No, Michelle, (may I call you Michelle?) you're not prejudiced against nurses. You're not trying to remind people that you are a Big Doctor Person. You're just trying to stay warm while not confusing people about your role.
I don't know what it's like in your facility, but in mine we can wear pretty much whatever we want (the RNs, that is) under our white lab coats or scrub jackets. I tend toward scrub tops with sushi prints. Some folks like, yick, teddy bears. One woman wears tops with glow-in-the-dark alien faces on them--she works nights. The docs wear OR-distributed scrubs or street clothes under their lab coats or, yes, scrub jackets.
Sometimes it's hard to tell us apart, pity the poor patients. I get called "Doctor" at least three times a week, more because I'm a little older than the other nurses and hence have a few more dark circles under my eyes. I look more like an exhausted resident to a gorked-out patient, I guess. One of my male resident colleagues gets called "Nurse" at about the same rate, probably because he looks well-rested and doesn't have pockets full of *stuff*.
It *is* all about truth in advertising. Clothes make the person in the hospital.
Get you some of those silk long undies and a scrub jacket, then have the scrub jacket embroidered with "Dr. Michelle Au". You'll stay warm and there won't be any questions, at least not from the observant.