Am I big enough to fit?

I really like Brandy Melville but there is just one thing stopping me from shopping there... I am extremely tiny for my age (17) I'm 4'8 and I weigh about 85 lbs (if you think I'm underweight I'm not since I'm only 4'8 being in the 80's range is normal for my height) Anyways I am really afraid that I the clothes will just slide right off my body because I'm just that short :( Btw my torso if longer than my short o'l legs.. If that makes any difference lol