I would definitely start working out hard b3000, and hit the cardio A LOT. Concentrate on cardio over the next 6 months - 30-45+ minutes a day 5-6 days a week. Start eating right, drop the sodas and junk food, just eat clean. You should drop down to about 13% or so and you'll definitely know whether it's going to go away. Be patient man, it might go away by your 21st birthday..you're still growing and body is still changing. A lot of times these things just go away over time. My body continually changed and grew until I was 23-24.. It is true you do produce more testosterone during your younger years and it just seems to me that your a bit overweight - get that in tune and you'll be fine man.
Also, if it's just squishy - puffy and easy to squeeze around the area, it'll probably just go away on it's own. If there's a hard lump behind the nipple, then it probably won't and trying letro may or may not solve the problem. If you do seek out a doctor, look for a plastic surgeon who is on your medical plan. Most of the time, insurance will pay for an examination - and it's better you are seen by a p.surgeon than a general. My gyno removal was covered by my insurance bc/bs ..