Can I Be Considered an Adult

I am a girl 18th years old. If you see from my age, definitely, you will think that i just graduated from senior high school. But the actual, i am student 3rd semester at Hamka University. So it the means, i got early for my elementary school and i graduated from senior high school in 17th years old. I feel happy with my age, but sometime i feel complicated to adapt with my friends who older than me. My friends opinion's when i viewed from the body and how to talking, I do look grown and do you know....???? I happy to hear that, because it the means, i have been adult. But if i remember my habit, that i often cry because a minor matter and my hobbies to fight over the toys with my younger sister. I feel doubt if i have grown. Do you know guys..??? When i getting together with my attend classes, i often pretend to be adult, but my childish nature suddenly turn up when i was around my family and the peoples who spoil me over. So once more i want to ask to you,,,Can i be considered an adult???