She may very well be going into heat. Jamie's first heat was at 11 months. My only suggestion is to KEEP THEM SEPARATED by a heavy closed door and DO NOT leave them unsupervised!

Can you call your vet to see if you can get his appointment bumped up a little earlier? I'm sure that will definitely help. Can you get her in too to be spayed? Because trust me, a female in heat is almost worse than an intact male.

If she is going into heat please be sure to keep a hawk eye on her, not just from your male dog but from other dogs as well!