What you are talking about is absolutely normal. If your nipples do not become erect with either stimulation or cold, then releasing the bands holing them in place may be in order.
Dr. Taranow
Moderate enlargement can be achieved with nipple augmentation using local tissue in the form of local flap(s). Filler would create some enlargement but not of the kind you seem to have in mind. In person consultation with a board certified plastic surgeon familiar with nipple...
