Hi apurv09.
It's confusing to score so much lower on the real GMAT than you did on your practice tests. However, as sure as day follows night, you'll be able to sort out what occurred, address it, and achieve your score goal. So, let's start that process here.
It's quite common for a test-taker to score considerably lower on the real GMAT than she or he had scored on practice tests, and this phenomenon occurs for various reasons.
One thing that could have occurred is that, on test day, you simply had an off performance similar to your performance on the test you took after your break from preparing on which you scored 660. In that case, it would be likekly that, if you were to simply sign of for a second GMAT 16 days after this recent one, you would score closer to the upper range of your practice test scores and achieve your score goal.
On the other hand, it could be that the GMAT revealed gaps in your knowledge or skillset that the practice tests didn't reveal, and there are various possible things that could be going on.
For example, one of the most common reasons why people's verbal scores on the real GMAT are lower than their scores on practice tests is that their verbal preparation somehow prepared them for practice tests they took rather than for the GMAT itself. I'm sure you're wondering how you could prepare for one without preparing for the other, and one answer is that much of what's said both in informal discussions of GMAT verbal and in GMAT prep courses is based on what appears on the official practice tests. So, it's common for people to learn these things that apply to the verbal section of official practice tests and score high on those tests but not as high on the real GMAT, which can do things in verbal questions that the practice tests don't.
For more insights into why your score on the real GMAT isn't as high as your practice tests scores and what you can do to hit your score goal next time, see this post.
Why Was My GMAT Score Lower Than My Practice Test Scores?For some insights into how to prepare for GMAT verbal in ways that result in consistently high verbal scores, see this post.
How to Score High on GMAT Verbal