I wouldn't worry about it. It sounds like all your daughters teeth are coming in pretty late. My son is 14 mos old and he sprouted his first tooth at 5 1/2 mos old and by the time he was 8 mos old he had 7 teeth. Now at 14 mos he has 9 teeth, and the two that just broke through are the ones behind his canine (eye) teeth on the bottom, his eye teeth are not in yet. He has 3 front teeth in on the bottom and we are STILL waiting for the fourth to arrive, its been over 5 mos since the other one came in and there is still no sign on it. If you take her into the dentist you could ask about it, but most likely it not an issue and its just something that will come when its good and ready! Good luck!
PS: I am also due in Dec with our second! How exciting!