How to even out my breasts without surgery?

Hard to do.: What we can control as individuals is our muscle mass, by exercising one side more than the other. Muscle mass can increase the local fat burning in that area. Even then, this 'change' is not exact or can be quantified easily to even out 2 different sizes. In terms of mammary tissue I don't believe there is non-surgical management to increase one size more than the other.