Looking for a gay-friendly, aware and gay-knowledgeable doctor is a very legitimate wish. While I can't help in Austin, I endorse the OP's goal.
I deliberately selected a doctor here in South Florida whose practice is mostly gay men. Indeed, they are mostly HIV+ men, which has caused some people to erroneously assume I am poz.
I don't give a s***. I know what I am, and I have the doctor and medical care I want. Plus, she's the Medical Director for the SMART Ride to Key West, so if I have some medical issue along the way, my own doctor is right there, who knows me and my history. It's been a comfort for 3 years now knowing she was on site if I needed her.
Whereas I know the horror stories, from friends, who were badly treated and verbally abused by homophobic doctors. So let's help the OP simply find a gay friendly doctor in Austin, OK? And a little less editorializing about gay-friendly doctors. He asked a simple question -- now let's answer it simply, shall we?