Thank you for your reply!
I wish I could retake the GRE, but I won't be able to retake it until February, and the deadlines fall on January...
In France I've attended "classe préparatoire" (it's a selective school where we prepare for competitive exams) for 3 years, and since 2010 I attend "Sciences Po Rennes" (another selective school in Political Science). During 2011-2012 I was an exchange student at UMass Boston.
The schools I'm applying to are University of Chicago, New York University, University of Texas, George Washington, Cornell University, and McGill in Montreal.