Tall and Skinny

I dont know about other tall girls but i have a really hard time gaining any weight. I have to eat all the time no matter what time of the day it is i am hungry and i eat. And no matter how much i eat i dont gain no weight, i could probably eat a whole elephant and still not gain weight. Even if i eat a big dinner or lunch, i am stuffed for maybe like 15 min tops and again i am hungry. Now a lot of people tell me its because i have a fast metabolism and that it will slow down when i will get older. But i would really like to have curves now and not be all bones and skin it just dosent look good!!! Who wants to look like a tree. Did anyone have the same trouble as i do now?