“but my school is very competitive.”
Your high school is NOT competitive on the level that Stanford is competitive. No high school is. If you go to Stanford be ready for a much higher academic level than you are used to. I was lucky that I went there as a graduate student because I was able to take only courses in areas that I am good at. If I had gone as an undergraduate I would have died in the English and History courses.
I agree with the post above that you should work to get your test scores up. Other than that as I was reading your post I was thinking “only chance is athlete or URM”, then I got to “URM”. With this and improved test scores you have a chance, but definitely have a plan B and a plan C.