Hi grv343,
To start, a 750 is just about the 99th percentile, meaning that 99% of Test Takers never score that high (regardless of how long they study or the number of times that they take the GMAT). By definition, that makes that score goal quite challenging. Thankfully, NO Business School in the world requires a score that high, so it's important to remember that the score that you "want" and the score that you "need" are almost certainly NOT the same score.
Assuming that this 530 practice CAT score is relatively recent (and accurate) - and that you want to score 700+ on the GMAT - then you will have to make significant improvements to how you handle BOTH the Quant and Verbal sections to hit that score goal. That work will likely take at least another 3 months of consistent, guided study though, so you might need to push back your Test Date. While the
OG Books are great sources for practice questions, they were not designed to teach you Tactics, patterns or the little 'secrets' to the GMAT, so you would likely find it beneficial to invest in a GMAT Course of some type (either Guided Self-Study or instructor-led).
1) When did you take this last CAT?
2) Going forward, how many hours do you think you can consistently study each week?
GMAT assassins aren't born, they're made,
Rich