Hi Ananya,
To start, since you are interested in some highly-competitive Schools, you would likely find it beneficial to speak with an Admissions Expert about your overall profile and plans. Those Experts should be able to answer your Admissions questions and help define the specific areas of your profile that could use some improvement.
There's a Forum full of those Experts here:
https://gmatclub.com/forum/ask-admissio ... tants-124/Statistically-speaking, raising a 550 to the point that you can consistently score 700+ will likely require at least another 3 months of consistent, guided study - and you'll have to make significant improvements to how you handle BOTH the Quant and Verbal sections. Thankfully, the GMAT is a consistent, predictable Exam, so you CAN train to score at a higher level. That having been said, you might need to consider pushing back your planned Test Date.
"Review" is an exceptionally important part of the GMAT training process; your ability to define WHY you're getting questions wrong is essential to defining the areas that you need to work on (and the specific things that you need to 'fix'). As such, I'd like to know a bit more about your last CAT. While a full Mistake Tracker would provide a lot more information, there are some basic questions that you should be able to answer (and the more EXACT you can be with your answers, the better):
After reviewing each section of this recent 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 could not remember how to do?
3) Because the question was too hard?
4) Because you were low on time and had to guess?
5) How many Verbal questions did you 'narrow down to 2 choices' but still get wrong?
GMAT assassins aren't born, they're made,
Rich