New York city?
You don't go to a specialized HS (Hunter, Stuy, Bronx Sci) in NYC and graduate low in your class and get a scholarship.
You're lucky to get into a school. MIT isn't looking for 12 people from the same HS, even if they're all geniuses...they want diversity.
I basically skipped a lot from the school, but because I was in the computer science (informatics) team, I've got A's (6) on certain subjects, because the teachers decided not to care. Other decided that I should be present more and I've got 3 or 4 - like C or D here in US.