Is the dx hypertophy? Sometimes when the left ventricle is enlarged (dilated) there can be reversed remodeling with medication. Often the LV is dilated when it is overworked due to high blood pressure, etc. Correct the afterload and the condition can be reversed.
If the heart is enlarged due to muscle mass growth, reverse remodeling may not be possible. Sometimes treatment can be an operation that surgically removes some of the muscle mass and provides more room for filling and may improve elasticity of stiffened heart wall (left ventricle). Cause low cardiac output and shortness of breath.
The upper chambers may be dilated due to impaired velocity and flow propagation from abnormal intra heart pressures and may involve valve stenosis or regurgitation. This can compromise cardiac output and cause shortness of breath.
There would have to be more testing, and your shortness of breat is due to your physical conditioning, and left ventricle size is overcompensation.