I work with kids everyday and have to talk kids out of this great idea all the time. While a few excel, they are very prepared and engaged early in determining their pathway and methodical course of action. There is not much in your posts that say you are ready to graduate early or on track for an acceptance to a semi-prestigious, highly to moderately selective college.
That work needed needed to be done in the past 6 to 18 months.
I love the idea of AFS or Rotary exchange and that has worked very well for some of my students. Those applications are also already in the works for next year, so if interested start to look at your options. The dates and school years can be tricky. We always recommend getting all of your application components in place prior to leaving so those items are mostly done and you are not trying to talk to your school counselor or principal with a 12 hour time difference.
Knocking out some college classes as dual enrollment is also a great option for next year and gives you time to research and visit colleges you should apply to in the spring and summer.
Not wanting senioritis is unfortunately too late - sounds like you may already have it. There are always a few juniors with early onset, but there are plenty of ways to get engaged in your community, so next year you are ready to apply to BU or wherever you have narrowed things down to with much better prospects.