Hi Arup,
I’m sorry to hear how things went with the GMAT.
Assuming that you took your official practice exams under realistic testing conditions, the results show that, on a good day, you are capable of scoring higher than V20. Given your description of test day, it seems as though your score drop was due to a combination of nerves and weak areas that were exposed on the GMAT. Although I’m unsure of how you prepared, it’s possible that, in your preparation, particularly in verbal, you did not really learn to do what you have to do in order to score high on the actual GMAT. Rather, you picked up on some patterns that were effective in getting you relatively high scores on practice tests. So, for you to hit your score goal, your preparation, particularly for verbal, probably needs to be more complete, meaning that you have to go through the various types of GMAT questions carefully to find your exact weaknesses, fill gaps in your knowledge, and strengthen your skills.
The overall process will be to learn all about how to answer question types with which you currently aren't very comfortable and do dozens of practice questions category by category, basically driving up your score point by point. When you do dozens of questions of the same type one after the other, you learn just what it takes to get questions of that type correct consistently. If you aren't getting close to 90 percent of questions of a certain type correct, go back and seek to better understand how that type of question works, and then do more questions of that type until you get to around at least 90 percent accuracy in your training. If you get 100 percent of some sets correct, even better.
For verbal specifically, you have to become more skilled at clearly defining the differences between trap choices and correct answers. Otherwise, you will get stuck guessing between two choices or be surprised to find that you incorrectly answered questions that you thought you answered correctly. Becoming more skilled in this way takes carefully analyzing all of the answer choices to lots of verbal questions to develop an eye for the logical differences between the choices. In other words, you have to go beyond answering practice questions and reading explanations to doing deep analysis of questions to learn to see everything that is going on in them.
Regarding anxiety, to help further manage your nerves, you could try some visualization techniques. Imagine various test-day scenarios such as getting stuck on a question, issues in the testing center, feeling pressed for time, or worrying that you’re underperforming. As you feel your stress responses start to kick in when thinking about these things, practice pulling yourself together and visualize focusing on getting correct answers.
When taking the GMAT, the best way to deal with stress is to get busy answering the question in front of you, focusing completely on the task at hand so that you redirect all of that nervous energy and naturally calm down. In other words, you distract yourself with a goal. Just tell yourself that all that matters is getting the correct answer to the question in front of you, and then when you have finished that question, take the same attitude toward the next one. Focus on winning each “mini-battle” and you won't have time for anxiety. If you can win enough of those battles, you can win the GMAT war, right?
You also may find it helpful to read the following articles:
how to limit GMAT anxietyhow to score a 700+ on the GMAT