Cynthia,
you didn't mention whether he had sisters or brothers, what are the influences on him at the moment, does he watch particular programs on tv, (that's television, not transvestite), family environment. There was a great British series years ago called SEVEN, the premise of which was "give me a child of 7, and I'll show you the adult", and it was extremely accurate over the course of 5 or so seven-year periods.
Does anyone talk to him about why he's interested in dolls and dresses? We all go through phases in life, and he could grow out of it. I started in my teens, had a very long "dry spell" and started up again in my 60's.
As the others have said, support and a loving environment will do more than a whole passle of doctors generic phrases.