How to look older

I'm 27 and am a highschool teacher. I'm 5'2" and super skinny because of a fast metabolism. Every single day I'm confused for a student and hear how I look younger then most kids multiple times and it's so annoying. People usually assume I'm about 16. I have two kids and really want to look older. I dress like an adult and carry myself like one but i feel like sometimes people dont take me seriously because they forget I'm an adult even if i look like a child. My husband is 10 years older and looks his age,people think hes my dad or we get weird looks. If anyone knows how I can make myself look older I'd love some tips!