Unexpected drop in test scores. Experts, please help!

[swk91]

Hello, I just gave my Gmat exam recently. Although I expected a score of around 730-740 (700 minimum), the score was just 600(q48,v25,IR6!! And then everything around me became blank. I am planning to take a test again after a month or two so experts please help me to identify my problem and steps to be taken to reach my goal. Below are my informations..
I first became familiar with GMAT around 9 months ago. I joined GMAT classes offered by a local institution. After few classes I found that I was strong in Maths and average in English. My first mock test score was 690 (GMAT PREP2) quant 50, verbal 33. The score I obtained was based solely on the few classes I had taken and on the strong mathematical background I had. There was no preparation from my side. As I work full time, I was busy in my office, nevertheless, I practised English and Maths from the Official Guide and notes from the instructor. Next I gave GMAT PREP 2 and score 680(Quant 49, verbal 34). The next mock test was on March 22 (GMATPREP 2 and I scored 660 Quant 48, Verbal 32). I was shocked seeing my score since without preparation I had scored 690 and after I worked so hard on the Official Guide 13th edition and questions from the Gmatclub, my score went down. Once again I decided to take PREP1 on Apr6, I scored 680 (Q49, v 34). All these test were taken without AWA( I did the IR - same questions though). Worried about my performance I met my instructor. He told me not to schedule an exam until I hit 700 level. He identified my weak areas seeing my practise test review and OG mistakes and gave me SC questions relating to modifiers, comparison, 3 LSAT tests for CR and Reading comprehension.
After practising those materials, I decided to give another test. From now on, I started giving full length tests with AWA, IR and 8mins break. I gave the Prep1 test on Jun18 and scored 710(q50, v36). And again Prep2 on Jun 23 and scored 720(q50,v37). Then I scheduled the test for Aug 3. I started practising from the 8 series both quant and verbal. I bought prep3 and prep4. I took Prep4 on Jul 14 and scored 710 (q50,v36). Next I gave Prep4 on Jul19, scored only 660 quant 50, verbal 29 - I got 10 out of 13 last questions. This was because I saw a hard question at number 28 and thought that my performance was extremely well (may have affected my psychology). I gave the Prep4 again onJul 21 and scored 770- Q51, V42 ( inflated though - I knew all those answers). Then I gave the free MGMAT test on 22nd and scored 670(q46,v35). I once again switched to prep1 scored 760 and prep2 scored 770. I felt I was fully prepared for achieving my 730-740 level. I revised the notes I had made from the 8 series, regularly practised from Gmatclub, reviewed each test for the mistakes I had made , revised my institution's notes.
On the test day, I couldn't sleep. My test was scheduled on 10 am. However, I was up 3 am(fear may be). IR and AWA went well.(Took full 8 min break and ate banana, sandwich)
I found quants tough and made silly errors, which I never made during my practise test. I later corrected the errors by rechecking the answers. However, I was nervous for questions I easily did during my mocks! Again I took full 8 min break (ate my food again). Then came Verbal. I was going smooth for the 1st ten questions. I found them easy. First 10, 55 min remaining. Next 10 was ok but behind schedule, 35 min remaining. The last 11 was nightmare. 11 questions 16min remaining. I didn't get the time to properly analyze the questions and choose answers through skim reading.
During my 1st mock, I found that I was good at CR and RC. My problem lied in SC. However, by the time of my last mock, I found that I was strong on SC and RC but got weaker comparatively on CR.
My self diagnosis says that nervousness, lack of sleep, fear of facing the exam and most importantly time management were the reasons for my nightmare scores. I have read the MGMAT time management article, however never followed it during my mocks. I generally used short SC questions and easy CR questions to manage time, if i was behind schedule.
Please MGMAT experts, help me on how should I be approaching now. I plan to take retest on Sep 18. And I seriously do not belong to just 38% above all test takers on verbal. Please help!! I will provide all additional information needed to diagnose my problem. I will do whatever it takes to reach my target score..

[swk91]

These are my MGMAT diagnosis for verbal and quant
s17.postimg.org/foqxzuua7/verbal.jpg
s22.postimg.org/jsx1utu69/quant.png

[das.abhijit34]

Experts please help. I had a very similar experience on the test.

Thanks,
Abhijit