First, I want to say: thank you for being an ally to us.

*bro-hug*

In regard to feeling self-conscious if others misperceive you as gay: just ask yourself what is the reason for your discomfort? If it's because you're concerned about your potential physical safety, or if it's because you are still seeking a heterosexual companion in life (and want any interested women to know that you're single/available), or if it's because you are dreading the prospect of learning which of your (supposed) friends or acquaintances are actually anti-gay themselves...I don't view that as anything that you should be ashamed of.

As a gay dude, I feel that the best way you can continue to be a straight ally is to continue what you appear to be doing: call out those who use "gay" or "homo" as pejoratives/insults, and maintain platonic camaraderie with any gay or bisexual men with whom you wish to form a friendship. Those steps are the best and truest ways to help bring the LGBT community closer to overcoming societal adversity.

*another bro-hug*