Graduate with your current HS class, so you are under less pressure this year with your classes, etc…just be a junior and focus on keeping/getting your grades up.
Explore what AFS and Rotary offer. See if it will even work out or of interest. The dates are all different. Some are only half the year. Some go from January to November (too late for that).
You can take dual enrollment classes this summer or when you come back, too.