Seven months is probably about average but it does depend on the breed of dog. The earliest I've seen in our ranch working dogs here in the U.S. is six months. The season last, usually , about 3 weeks, but can be somewhat shorter. The fact that you aren't observing discharge is probably misleading in that the female tend to keep herself cleaned up.
It'd be best to keep her isolated for another week or so. Your neighborhood male dogs will be the telling indicator. When they stop hanging around and showing interest, she'll be safe.
Best of luck!