hehe dear, I think you are
plenty slim. You should try pillates or yoga! You don't have to buy anything other than maybe a ball for pillates and thats only around ten dollars. Its really good for toning-- which I think is sexy more than just being thin.
I'm doing yoga right now because I wanted to try something new. It's a little out there for me but it's a lot of fun. Who knows, maybe you'd love it?