I'm saddened to hear of your problem.
Your surgeon was sculpting. It is always easier to go back and take off a bit more, but not possible to but it back if too much was removed. If an error is to be made, it is best to err on the side of caution. Talk to your surgeon and see what you can work out.
Meanwhile, your situation give me an opportunity to say something else as well. The greatest effect of Gynecomastia is what it does to the self image. There are virtually no physical effects for most of us but we suffer emotionally. I personally think that most lads should see a Psychologist somewhere along the line if our condition causes depression etc.
Good luck