I have puffy nipples but I don't know if it is fat or gynecomastia.

It is really impossible to say without an exam. In general, the nipple and areola tissue will contract when stimulated by either digital pressure or cold temperatures. Nipples that shrink when pressed are normal. Elongated nipples may just be elongated nipples. Many patients have nipples that are larger than average but do not have gynecomastia. Gynecomastia refers to overdevelopment of the tissue deep to the nipple and areaola that causes a feminization effect on the chest of a male.

Gynecomastia is not fat ,but gland,
How should I choose a surgeon?
Selecting a surgeon is as important a choice as the decision to undergo surgery. Choose carefully only a board certified PLASTIC SURGEON. The decision is yours. What follows is some advice to assist in making your selection.
1. Experience matters. Choosing a surgeon who has performed over one thousand gynecomastia cases increases the likelihood that they have seen a case similar to yours in the past. Selecting a surgeon whose practice is focused on gynecomastia exclusively is also an indicator of experience.
2. Results matter. The more before-and-after pictures a surgeon displays, the better. Pay attention not just to the number of pictures, but whether the surgeon is confident enough to show multiple angles of the same patient.
3. Gynecomastia surgery Reviews matter. Have patients reviewed your surgeon? Did those patients undergo the surgery you are considering?
4. Expertise matters. Is your surgeon recognized by the profession as an authority in the field? Are they certified by the American Board of Plastic Surgery? Have they authored books or medical journal articles regarding your surgery?

We hope these guidelines are of assistance when you are selecting your surgeon. When undergoing surgery, it is very important to be realistic about your expectations. Past results are not a guarantee of future results. Also, revision surgery tends to be significantly more difficult than initial surgery.