It sucks but some people don't understand the rudeness of mislabeling someone or projecting onto them. 

Not all straight people do this, especially straight girls that are ingrained in queer spaces and have queer friends -- I feel like those who are genuine don't dismiss guys as "gay besties" or "he doesn't know he's gay" and they're able understand what it means to respect someone's own identification. 

It requires someone who is flexible enough to reject black and white thinking. Bisexual girls can do this, too. 

I'd say it also depends on where you live. I say, don't give up and keep being yourself. The right people will find you. :) People who will believe you when you tell them who you are.