you'll have heard us talk about how an eleven year old can be such a fast swimmer despite having very little strength compared to an adult. One of reasons they can do that is that kids don't place limitations on themselves, every time they go to the pool they walk out excitedly on to the poolside with a clear head, jump in the water, go for it and see what they can do.
Maybe you've settled because of your age, your inexperience, your talent, your training time, your gender or your height. Are you sure the barriers you feel are not entirely self imposed? Take a leaf from that eleven year old's book: enjoy every moment, work hard, keep an open mind and believe you will become a better swimmer...and you will.