Calling her “Dr.” is pretty ridiculous. Personally I think that title is for folks who have gone to med school, although I realize phDs love to hear that before their names!
I've found that other than in academic settings, most PhDs in everyday life don't necessary want you to call them "Dr", unless they're douchnozzles in love with their credentials.
No. Call me Dr. Jackson and I will consider you a wormy suckup and tell you to call me Andy from here on out.
That's because "PhD" sounds too much like "FUD" (fear, uncertainty, doubt) or "FUDD" (Elmer - I'm hunting wabbits); and NRD ("not a REAL doctor") sounds too much like "Nerd" which is just piling on.