The more I study the worse I get ,esp Verbal

Hi everyone,I really need your advice on my Verbal score. I retook the GMAT yesterday got a disappointing 600(Q-46, V-27). I could only improve my score by 10 points and my verbal score dropped from 29 to 27,that was the most shocking development. My first diagnostic gmatprep score was 640 , so all the learning is proving to be counter productive.

My mock test scores were --
MGMT mock#1--620 [Q-39, V-35]
MGMT #2------670 [Q-44, V-37]
MGMT #3------690 [q-49, v--38]
Gmat prep1---620 [q--44, v-32]
MGMT#4-------700 [q--43, V-41]
gmat prep2---690 [q-48, v-37] (one week before the test)
MGMT#5-------720 [Q -47, V--42] (four days before the test)

Can't understand the cause of the huge discrepancy between the mock scores and the actual exam. This time around I had solved the OG 12 ,timing each question and revised all the questions I got wrong, questions I had to guess and the questions I solved after the 2 minute time limit.

Resources used--
OG 12, OG 11( RC and SC sections ) , OG verbal and quant supplements, Manhattan Gmat- SC, Number properties and Equation guides, Powerscore CR Bible,and Kaplan 800/Advanced.

Test day:---
AWA was good, Quant was ok and I had expected something around 47-48 since I couldn't solve 2-3 tricky geometry and time-rate questions, so i knew that 49 wasn't happening (actually got 46).
Verbal went smoothly. CR--got the usual strengthen, weaken , paradox questions and couple of parallel reasoning and abstract reasoning questions. Didn't get any Boldfaced and speaker 1 vs speaker 2 questions, so that did concern me a little, but one cannot say for sure how the test is going. So didn't let that affect me. SC-- except 2 SC questions, I could spot the spilts and traps in rest of them , so thought I was doing fine. RC-got 4 passages on different topics as expected, nothing out of the blue.
The end result a pathetic 27. If I could gauge a bit that the test was going in a wrong direction I would have spent a little more time on questions or cancelled my score. But was really shocked with the 27.

Can't understand what I am doing wrong. In spite of making constant progress in Manhattan mocks and GMAT prep mocks (last GMAT prep2 score was 690 --48q, 37v) how the actual score can be so low (around 100 point difference). Moreover, I don't know what section in verbal was wrong. My guesstimate is that for scoring a V-27 in gmatprep software one usually gets around 20-21 questions wrong. But is it-- SC, CR or RC where am I making mistakes I can't understand. Are the gmatprep practice test reliable test performance indicators?

Any advice would really be appreciated. If I plan to retake I should know what am I doing wrong so that I can work on that weakness. I did take the necessary study breaks for 1-2 days/week, so I don't think I am over doing it. Please Help!