Welcome to gyne.org, Alt Solution.
No one can say what the future holds when talking gyne surgery, but the odds are with you. Assuming you go to a very experienced board certified plastic surgeon and get good quality surgery right off the bat, then in all probability, you won't be needing anymore surgery.
What would make it MORE likely to need surgery again? One thing has already been mentioned....gaining too much weight. Also, certain meds have been associated with gynecomastia, and if you take them, you could begin to grow again. Of course, the main thing to stay off of would be the steroids. But the main thing you need to make sure of prior to having surgery is that your gyne is STABLE.....as in, make sure it has been the same for at least several months (i.e, no growth/swelling/tenderness) prior to surgery. If someone with active (growing) gynecomastia has surgery too soon, then the tissue will continue to be stimulated after surgery and growth can return. Then, you've wasted all the time, money and trouble you went to. So you want to make sure that your condition is stable before considering surgery.
As far as the anti-depressants you listed, I don't believe I've ever read anything that says those types of meds increase gynecomastia.
Sure, a doctor can check your hormone levels, and they probably need to be checked prior to surgery. Your family physician should be willing to do all the usual blood tests when it comes to looking at hormone levels, however, some docs don't feel comfortable doing it and may want to send you to a specialist that deals with such matters (endocrinologist).