Don't stop playing sports, if the imbalance is caused by them. The volume of the chest remains the same. Do not attempt to lower the shoulders and Crouch, you only worsen blood flow to organs and reduce lung capacity. Keep practicing, changing their orientation. If you develop the power, now important stretching and endurance. Do the exercises with small weights or without (depending on the initial physical training), develop flexibility. Look at the dancers: the figures are stacked enough in proportion, but due to the stretching of the muscles of the chest does not seem overly wide. Try the same exercises that are used in classical ballet.
Corset. Preferred therapeutic or used as underwear. Wearing such a type which pulls it back, and shoulder girdle. Tie waist and upper thighs will only aggravate the impression of imbalance due to the exaggerated difference.
Choose dresses with thick straps, and even better with the shoulders. Thin straps or no visually expand the shoulders. The preferred dress is dark, but not black – it would make illusory the border of your shoulders more narrow.
Focus on the lower body, particularly the hips. Make visually wider by using bright colors, horizontal stripes and loose silhouettes. Wear a wide bright belt.