Nipples: is it normal if one of the nipples is becoming slowly (through the years) larger or smaller than the other one?

Probably ok: This is not unusual. However if there are any associates masses, nipple drainage or bleeding, scabbing, or armpit swelling, etc....I would seek the e ablution of a general surgeon or gynecologist. If you are over 35, you should consider a mammogram and possible ultrasound.

It is not abnormal: Breast tissue weight can be heavier on one side to cause "stretching of the skin envelope. This would be noticed possibly as sagging of thalthough breast shape size, etc. Are usually symmetrical, at least 10% of women have some assymetry . Many may be a full cup size different. Correction of nipple size or even areola (the flat, colored portion of the nipple complex) size is easily done surgically.