Hi yashp2995,
From what you've described, you've worked through lots of practice questions, but it's unclear how much of your work has focused on learning the Tactics, patterns and all of the little 'secrets' to the Exam. 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.
Beyond those points, there's also the question of how you've been taking your CATs. When you took your CATs:
1) Did you take the ENTIRE CAT each time (including the Essay and IR sections)?
2) Did you take them at home?
3) Did you take them at the same time of day as your Official GMAT?
4) Did you ever do ANYTHING during your CATs that you couldn't do on Test Day (pause the CAT, skip sections, take longer breaks, etc.)?
5) Did you ever take a CAT more than once? Had you seen any of the questions BEFORE?
Thankfully, the GMAT is a consistent, predictable Exam, so you CAN train to score at a higher level. To hit your score goal, you will likely need to invest in a GMAT Course of some type (either Guided Self-Study or instructor-led).
GMAT assassins aren't born, they're made,
Rich