Listen, I came here from another country, and in Asia, we're smaller THAN NORMAL AMERICANS. New land. New friends. New surrounding. New school. With just the clothes on our backs!
I was older, than them, I was smaller than them, but that didn't give me negative about myself. I was being myself. I did lie by 1 year younger than my own age, since we didn't have 7th & 8th grade there, we went straight to HS.
"I don't know what can I do to look older," You can't change them, but you can change you, by being yourself! Be positive instead of trying to fit in and trying to look older. We're born to be UNIQUE, not like everyone else.
If I can do it, so can you!
But does it really matter what I say or what they think about you?
One think if you'd like to create new hairstyles, by putting your hair up in many different styles, that will make you look more mature & older. No pony!
Now that I'm 64, I still look like I'm 40, but that's OK, because my parents were in their 90's and people thought they were in their 70's. That's a very positive thing, because people always want to look YOUNGER, until they start guessing your age!