You can call AAMC and ask. It's not like they'll accommodate you for being an "advanced" English speaker vs native. I'm not a native speaker and picked advanced, nothing happened. Relax, won't change your test and how it's taken.
I will not affect you, it is simply used for demographic data by the AAMC. AFAIK the schools will not see it. And adcom can be more explicit. Don't stress over it, focus on bigger things like studying and practicing Qs.