If you are dissatisfied, I agree with DavidDoes. Lean bodies build shape so, so fast. Every pound of muscle shows immediately. Just lift heavy and eat a little more (not a lot more, I'd say one extra hard boiled egg a day or equivalent). It's a short jump and few pounds from twink to male model (fashion model not athletic model) build.

If you just mean you don't care about physical appearance, but aren't attached to being petite, I'd still advise getting in shape because exercise helps mood and will probably help your confidence.