I have worked with my adviser for a few months as a graduate student. Everyone, including her other graduate students, seems to call her by her first name. She never expressed a preference to me, so I've been calling her "Dr. Smith". She signs her emails with her first name.
I am worried that I am being awkward. I don't mind calling her "Dr. Smith", but during meetings where other students are present, it would be jarring to call her "Dr. Smith" while other students use her first name in the same conversation. So far, I have managed to avoid this issue by choosing my words very strategically to avoid directly addressing my adviser at all.
I don't wish my adviser to think that I am making some sort of statement by being unnecessarily formal. On the other hand, I don't wish to appear too informal either. Apart from that, once you've addressed someone by their title for several months, unceremoniously switching to their first name out of the blue seems like it would be very strange.
Is there any tactful way of resolving this predicament, besides waiting and hoping for the adviser to express a preference? I am in the US.