Adults shouldn't think this way right? (mature answers please)?

I am 33 and i still worry obsessively about what people think of me. My friends my age keep telling me I should be over this, that I worry about things the way teenagers do. It should be comforting that I don't have to worry about being myself now that I'm a grown up but I can't stop worrying about social issues. I also avoid people different than me (not racially or culturally) but people with different tastes in clothes and music etc... because I worry they might not like me. Do I have social anxiety? I mostly stick to just people I know extremely well and avoid new people. My friends tell me I'm not acting my age worrying about trying to be "with the cool kids." They ure me us adults can rest easy now and be who ever we want.