I'm younger than you, but in about the same boat. I've even had some of the same experiences - child's menu at restaurants, "you'll be glad when you're older," being thought of as much older when I presented as female, having an older mentality, etc. My facial features are fairly androgynous and I usually have smooth, ridiculously soft skin.
I've found that what helps people perceive me as older is dressing in somewhat more of a masculine androgynous style rather than just 'man' clothes. Also, hair is important. When my hair is somewhat shaggy, not only do I pass even better than when it's short, but people also think I'm older. I think that it's mainly because I'm emulating a sort of vaguely gender-bending (effeminate male)style that's fairly common/popular at the moment. I'm not saying that you should change your style or anything. I've only noticed that this works for me because that's the style I enjoy anyway.
I can empathize on the lack of facial hair. My brother had a full goatee before entering junior high (no joke, he took after my mom). My dad, however, has very little body hair and it takes him a week to grow a really short, scraggly beard. I took after my dad in nearly every physical way except being born male. When a stranger meets both of us, then that person thinks of me like my dad, so he/she perceives me as older. So, find some feminine looking guys who have smooth, soft skin and try to be somewhat near them when meeting new people. You'll look older/more masculine by comparison.
I've heard that shaving your face (despite having a lack of whiskers and whatnot) will help since it'll make you look like a clean-shaven young male, but I've never tried, so I can't vouch for the success. If you go out in the sun a whole lot, over time your skin will get a little more leathery and wrinkled than someone who never goes outside, so that could help. On the contrary, if you make a big deal out of never going outside, then people will just think you're smooth and soft from that.