bastian: I agree with your wife. I am a 9.5 incher and have been told by most who talk about me and my dick that I am large. According to anything I have read about average penis size, they claim that 6 inches is average. Since you are 3 inches larger than average, I would guess that makes you a large.
Maybe in your neighborhood, 9 is medium, but I would think that you could move this forum to meetings in your neighborhood garages.