Help make sense of how the stigma of homosexuality makes me hold my tongue often.

For a year or two now I've been openly gay as a freshman in high school, and around my friends and most people I act myself (I'm not really too -fem- though). However whenever I'm in social situations I tend to hold my tongue even though I consider myself to be open about it and I'm fully out. It might stem from how my family speaks about the LGBT community, but I feel embarrassed talking about how I like guys whenever I'm in situations like a classroom where it's really quiet and everyone can hear me. I hate how talking openly about being homosexual is so taboo, and if anyone can help me make sense of this please respond. :)