I'm jealous of my perfect younger sister?

There's a seven year age difference, but I'm jealous of my little sister and I don't know what to do. She's 13 and I'm 20. She's still in puberty but already showing signs of becoming absolutely gorgeous. She has always been called pretty by everyone we know; I have many memories of going to family parties where all my relatives rushed to her to fawn over her beauty, only to look at me and comment on how "smart" I am. She has never had any problem garnering attention, and is a little spoiled because of that. Don't get my wrong- she's not conceited or anything, but she knows she's got the looks. She is really sociable and makes friends easily, and boyfriends even easier. She's only 13, but has had more male attention and more boyfriends than I've ever had in my 20 years, which is really depressing because guys hardly ever look at me, and she's got them falling at her feet! She has no idea what it feels like to be bullied, ignored, or feel ugly or worthless because things have always come easy to her.

I, on the other hand, am not as blessed. I am short and a bit thick (kind of "stumpy") and she is tall, lithe, and lean; we're the same height right now. When I was her age, I had horrible, horrible acne and it has gotten better with time but I still have pretty flawed skin, while hers has remained perfect. I get bad eczema and she doesn't, I have a chubby, round face and hers is cute and heart-shaped. She's even the only one who doesn't have to wear glasses in our ENTIRE family, while I've worn them since I was five. Also, I was teased and lonely growing up (and am still not-so-confident to this day) because of how I looked and how debilitatingly shy I was. She has never lacked in confidence or friends, and is one of the popular girls I always longed to be when I was her age.

I know it all sounds so stupid and trivial to be depressed over this, especially since she's my younger sister, but it's actually harder BECAUSE she's my younger sister. I feel like, as the older one, I should be the one setting the example. But I feel inferior to her (and I know this has to do with my self-esteem issues as much as anything else). I compare myself to her even more since we're related, and I can't help but feel like life is so unfair because she got everything and I got nothing :( What can I do?