I'm almost 18 but i feel like i still look like a kid?

i am going to be 18 soon and i feel like i still look like a kid. i dont no what makes some people my age look more of an adult and some people (like me) look like a kid still. i go tanning every once in awhile but most days of the year im really pale, i dont no if that has anything to do with it. i mean im not super short im average height and i dress nice, but i feel like i look like a little kid who dresses nice you know? i dont wear alot of makeup either and my clothes arent imprinted with holister or band names or words in general. i dont no how do you look more like a women and less like a young adult? Is it just an aging thing? i mean do some people always just age faster and generally look older? idk help me out! i mean i wear heels alot too that probably helps my cause except i live in the north....so half of the year my city is buried in snow and if you dont no what thats like well let me sum it up...you really cant wear heels in the snow even if you get boots if its too cold or too deep your just going to slide and fall. but anyway any advice, i want to look just mature for my age like in that simple yet elegant way.