There are unconfirmed reports of sightings in the Brazillian rainforests of shemales at least 7 ft tall, of course this might just be down to whatever they smoke in that part of the world and wishful thinking...

To be serious for a minute, I have a female cousin who is taller than you and, apart from the usual gags that any tall person gets, nobody has ever asked her if she's a guy. So if you're thinking that you might not pass if you're more than 5 foot 3 or something, think again. People come in all shapes and sizes, y'know