Hi Daniriccardi,
Your Quant Scaled Scores make me think that you're approaching the Quant section as if it were a "math test" (and it's really NOT a math test). While you will do lots of little math steps to answer many of the Quant questions that you'll face on Test Day, most of what you'll see are strategy questions. They're built around patterns, shortcuts and other factors that will reward you if you're a flexible thinker. Many Test Takers who self-study with books get "stuck" at a particular score level because the books aren't forcing them to think in a strategic way.
With your timeline and the schools that you listed, you can absolutely hit your goals and there are a variety of approaches that can help you to do it. Before you purchase any new products, you should take advantage of the free resources (practice problems, Trial Accounts, etc.) that the various GMAT Companies offer. We have a free trial (at
www.empowergmat.com) and all of the other Companies (Veritas, Kaplan, MGMAT, etc.) offer options. You should try them all out, then choose the one that best matches your personality, timeline and budget.
GMAT assassins aren't born, they're made,
Rich