Hi JL050594,
Studying for the GMAT now - far in advance of when you will actually "need" your Score - is a smart choice. By extension, you do not need to 'rush in' to take your Official GMAT, so you should make sure that you are comfortable with the overall content, Tactics and patterns first. Statistically-speaking, raising a 590 to the point that you can consistently score 680+ will likely require that you commit to at least another 2 months of consistent, guided study. Thankfully, the GMAT is a consistent, predictable Exam, so you CAN train to score at a higher level.
The Quant section of the GMAT is NOT a 'math test'; it's a critical thinking test that requires lots of little calculations as you work through it (and most of those calculations are based on standard Addition and Algebra rules). As such, you do not need to be a 'math genius' to score at a significantly higher level in the Quant section (and thus, overall), but you will almost certainly need to change how you "see" (and respond to) that section of the Test.
Since this was your first CAT result, I suggest that you study as you like for the next 1-2 weeks, then take a NEW CAT. Make sure to take it in a realistic fashion that matches-up with what you will face when you take the Official GMAT (take the FULL CAT - with the Essay and IR sections, at the same time of day as when you'll take the Official GMAT, if you will be at a Test Facility, then wear a face mask, etc.). Once you have that Score, you should post back here and we can discuss the results and how you might best proceed with your studies.
GMAT assassins aren't born, they're made,
Rich