To appear super slender either stand in "pretty feet" (ballet 5th position) or cross your legs - take a look at Us Weekly, everyone crosses their legs, and there's a reason! I learned these doing pageants.
BTW, Miss Muddy Paws is right only it took your klutz mom much longer to figure that out. I think you look CUTE! A very fine Dorothy indeed. You can send the costume to Katie...between college and YL, I bet it will come in handy. xoxoxo