Life unfortunately is hardly ever simple!!
The choice is between you, your parents and your physician. The best thing I can tell you, is to follow your physicians advise. If your physician feels that the best chance for a 100% recovery is the surgical route, then you need to consider that. You will need to walk on that ankle for the rest of your life.
Based on what you have stated, even if you went the surgical route, as long as you are at 100% by next December it should not be an issue whichever route you choose. Just remember that you need to be at 100%, if you are only at 90% you may run into some issues.
You are young and you have time. Focus on healing right now, and worry about the DoDMERB issue next year.