Hi Shravya,
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/From what you've described, your studies so far have been "book heavy"; unfortunately, many GMATers who study in that way end up getting 'stuck' at a particular score level. 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. The
OG books are great sources for practice questions, but they're not designed to teach you Tactics, patterns or the little 'secrets' behind the GMAT - for those, you'll need Course-oriented materials. As such, you would likely find it beneficial to invest in some new, non-book study materials for this next phase of your studies.
Since you have not taken any NEW FULL-LENGTH practice CATs/mocks over the last 2.5 months, we really need to better define your current skills, strengths and weaknesses. I strongly recommend that you take one of the Official GMAC CATs sometime soon (perhaps this weekend). 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 (or you can feel free to PM me directly) and we can discuss the results and how you might best proceed with your studies.
GMAT assassins aren't born, they're made,
Rich
760+: What GMAT Assassins Do to Score at the Highest Levels