Kenya said: "why isn't she spayed? if you are not a professional breeder, it is very important that you spay her.. regardless of anything."
Or... you could be planning to let her have a litter so she matures fully. There is absolutely no harm in it, and I'm reasonably certain you wouldn't just dump the pups loose on the street to join gangs and raise all kinds of heck. People are usually more compassionate and aware than they are given credit for. Besides, professional breeder is another name for overpriced dog seller. Anyway, you'll wind up with a less excitable, less nervous dog. Just speaking from experience, having grown up in the country and having raised several different kinds of dogs.
Could she have hit her heat and you not noticed? How mild can that be? I would ask a vet, but I wouldn't worry about her. Does she have interaction with other dogs? I've seen cats get downright obscene when they go into heat, but most of the female dogs I've had have been pretty mellow. Its the males that get worked up.