Do you think I should go for it?

I just watches Slum-dog Millionaire and loved it. At the end though, my Mom basically asked what we wanted most in life, even if it was something stupid. Well what I really want is to be a ballerina! I would just love to be able to dance like that! It's always been my dream but I didn't pursue it earlier because I thought my older sister would be mad at me. It's her dream, and she is a beautiful dancer. But every time I see her dance it makes me sad. Not only am I NOT a good dancer do to the fact that I have NO training, I'm completely inflexible do to growth spurts. It would take a lot of work to get into shape and then I also don't really have any ab muscle. It would take a lot of work, stretching every morning and every night. My complete devotion and me giving up a lot of reading time, which I LOVE! Do you think I should go for it even though I'm already way too old to REALLY be a good dancer like the kids that start at three and because I will be super tall when I grow up, way too tall to be a professional around 5 feet, when I'm already 5'4! What do you think?