C.S.
My son, was 6 in May, just lost his first tooth last Friday. He now has 4 others that are very loose. He's sort of moving down the same line as your daughter, his just haven't came out yet.
He has a girl in his class that as all ready lost 12 teeth and she just turned 6. All her front teeth top and bottom and her cananies are gone. Hers started falling out last summer. I don't think she's lost one in several months now. The new are all coming in.
Your daughters new teeth are probably right under the surface. Once they start to move the just push the baby teeth out at an alarming rate.
I really think your daughter is fine. Check with your doctor and dentist though to be sure, and enjoy being the tooth fairy!