Hi sofiahasan,
Earlier this year (in January), you scored 450 on a practice CAT and now you've scored 500 on the Official GMAT. GMAC has publicly stated that the Official Score that you earn on Test Day is within +/- 30 points of actual ability. Assuming a similar 'swing' in how your CATs function, these results show that you essentially performed the same each time (about 480 +/- a few points). Raising a 500 to a 650+ will require that you make significant improvements to how you handle BOTH the Quant and Verbal sections - and all of that training will likely take at least another 3 months of consistent, guided study. As such, you will likely have to push back your Test Date.
Before I can offer you the specific advice that you’re looking for, it would help if you could provide a bit more information on how you've been studying and your goals:
Studies:
1) What were your Quant and Verbal Scaled Scores on the Official GMAT?
2) What study materials have you used so far besides the books that you mentioned?
3) When are you planning to apply to Business School?
4) What Schools are you planning to apply to?
5) Going forward, how many hours do you think you can consistently study each week?
GMAT assassins aren't born, they're made,
Rich