In most women, the left breast is usually slightly larger than the right. Certain drugs that treat one type of cancer do not work with others. The situation is, I have one breast that's bigger than the other. Am I is that weird? No Woman Is Completely Symmetrical. Dr. Kirtly Parker Jones. One Of My Breasts Has Suddenly Grown Larger. My left breast has become larger than the right, and this happened within just a but that can produce pain, breast lumps, soreness, tingling, and other types of discomfort. To many, having lopsided breasts — where one is much smaller or differently shaped than the other — may sound a trivial issue, but Jane is one.