Are you annoyed people think you're considerably younger than reality?

I'm 24 but unless I get very dressed up, I tend to look around 16-18. I'm 5'8 & womanly curvy but have a babyface & sometimes get acne (which I don't think helps). I tend to dress simply and wear my makeup very natural. Plus, I have a squeaky, girly voice and apparently a generally innocent look I can't seem to shake off. I understand looking younger is good (in theory) but I've been known to have bartenders barely believe my ID and even ask if I was old enough to have a driver's license! I keep having trouble getting taken seriously at jobs and often wonder if this might be a partial cause. Has anyone else had similar experiences? Don't you find it incredibly annoying, especially when people you know are younger than you treat you like you're 12?