Yes, except a woman cannot be Mrs. "her first name" "her husband's last name". You are only Mrs. "your husband's names". Despite much that you see to the contrary, Mrs. Barbara Smith is incorrect. She would be Mrs. John Smith and Ms. Barbara Smith. Mrs. technically means "wife of...". The only time that you might be Mrs. Barbara Smith would be if you were a widow.
It is my understanding that you also stay "Mrs. Barbara Smith," but not "Mrs. John Smith" after a divorce. The rule about not being "Mrs. Barbara Smith" after marriage seems impractical, though it may be technically correct. I doubt many doctors, offices, etc., would be willing to file your records under "Mrs. John Smith," and it seems too bad to have to give up your "Mrs." title just to have the clarity of using your own first name. Of course, most doctors, lawyers, professionals, etc., address everyone automatically by first name only now... which I dislike. I tend to use "Mr." or "Mrs." until asked by the person to do otherwise....