I know the feeling. I got lucky with my partner. She fell for me, but only because she tripped on the wheel of my wheelchair.
The only way I can think of, is to get yourself out there and be really open (but not flaunty) about your sexuality. I mean don't spend your life in rainbows and t-shirts with crappy slogans, but at least answer truthfully if people ask and correct them if they assume you're straight, I guess. Aargh. Life is stupidly hard sometimes!
So (too) many people are raised to only believe they can be straight. I have had so many boys whose bodies I would love to put whipped cream all over and lick all over...
But yeah, it's sad, but it's just something we have to live with. You'll find a good girl some day soon.