Look at the Common Data Sets for the various universities you listed in your first post. NO ONE had a math SAT score under 500 at Brown or Yale last year. http://www.brown.edu/about/administration/institutional-research/common-data-set http://oir.yale.edu/common-data-set
I strongly suggest looking at test-optional schools. I also suggest ignoring the advice to drop your extracurricular activities (which are very strong, and which you obviously love) in order to pursue an unlikely score increase. Base your college list on schools you can get into with your existing profile. It will be much too late to start from scratch in late December, when most application deadlines will be pending.