Hi kcd,
My guess is that yes your daughter is gifted, likely profoundly gifted. I would recommended having her tested, preferably by a psychologist who works with gifted children. I had my oldest daughter tested at four. I was like you and did not realize until my daughter started preschool just how advanced she was.
If you haven't already been there, I recommend that you visit Hoagies' Gifted Education Page. There is a wealth of information on this website, but you may find the pages on identification and testing particularly helpful.
http://www.hoagiesgifted.org/ Summer
