How to Enlarge the Size of the Nipple? (photo)

From your photo, you nipple looks completely normal.  However, if it does invert at times or you would like it to be larger or permanently erect, fillers might be a good option to consider.  There is surgery to successfully correct inverted nipples as well, but that does not usually create a larger (diameter and height) nipple - it is done to keep your natural nipple from inverting.   I would seek a consultation with a board-certified PS who specializes in breast and nipple surgery to get options.

It sounds like you may have intermittent inverted nipples, which means your nipples invert sometimes but can become erect and not inverted at other times.  This can be corrected with an inverted nipple repair, which is a straight forward procedure that can be performed under local anesthesia in the office or minor operating room.  The tethering bands causing the nipple to invert are released, and the nipple is sutured such that it stays in the outward position with dissolvable stitches.  The nipple will no longer invert when this procedure is performed successfully. 
Sometimes after inverted nipple repair some patients desire increased nipple projection.  Patients who do not have inverted nipples but just want increased projection also make this request sometimes.  Fillers can be used to increase nipple projection, but they are not FDA approved for this purpose and considered an off-label use.  I would recommend an in-person consultation with a plastic surgeon to allow for a thorough physical examination and to make more specific recommendations for you.
Ziyad Hammoudeh, MD