Also how old is your daughter, and how are you using it? Sleep overs? Camping?

I grew up in southern Cali; I found that my 20 degree bag was usually too warm in that state - Texas might be similar.

Mummy bags are warmer, but tighter. I'd suggest going to REI or someplace similar, where folks can help demonstrate specific brands.

Personally, I've had good luck with the REI brand. NorthFace is pretty good too. In fact, I think (based on personal observations only) that REI tends to "knock off" NorthFace, but at much better prices. Plus lifetime warranty.