But you are an a young adult, in fact 18yr olds are always still consider teens since most high school seniors are 18. Also young adult includes college students.
So think about having the best of both worlds, teen and young adult at the same time, you can use whichever benefits you at different situations lol For example when I was high school senior I was 18 and me and my friends go to the liquor store I can buy scratch off tickets for everybody, so in that situation I loved pulling the adult card out, but when we went to the local bumper cars I pull out my student id card so we can get teen discount lol
Since you're a girl I'll tell you something that might be helpful too. One thing I like using when creepy men keep bothering me especially in public, I just say I'm underage so they better bounce before they catch a case lol. It works wonders, they even apologize before running away, I kept using it well into my 20s, since I do look so young.