Hi kreel11,
The problem you're describing actually happens to many Test Takers who use a "book heavy" study approach. Even the best books are limited in what they can teach you; they also can't force you to approach questions in a certain way and their explanations are often one-sided. "Your way" of approaching the Quant and Verbal sections has you stuck at this current scoring level. To make a big improvement, you'll have to change your tactics. This will likely mean investing in some new Computer-based resources and learning (and practicing) new tactics (right now, you shouldn't be working on 'advanced' material, since that's not where you're going to find the missing points that you're looking for).
After reviewing your last CAT, how many questions did you get wrong....
1) Because of a silly/little mistake?
2) Because there was some math/verbal that you just didn't know how to do?
3) Because the question was too hard?
Thankfully, the GMAT is a predictable, standardized Test, so you CAN train to score at a higher level.
GMAT assassins aren't born, they're made,
Rich