710 -> 690 -> target 750+: GMAT retake strategy? (w/ESR)

Hello there! Fellow GMAT takers and experts.

My score of the first attempt (mid-Feb 2017) of GMAT was 710 (Q50, V36, IR5), while the second attempt (mid-March 2017) was shockingly 690 (Q49, V34, IR7). I would like to apply to top ~10 MBAs in the US this fall, so I plan to retake GMAT in the next 1-3 months. My target is to score a minimum of 730 but better 750+ for my application.

A brief background
Non native English speaker. Social science major in college.

Preparation for the first attempt
I finished OG and OV and flipped through the MGMAT SC guide. It took me roughly 2 months (~9 hrs/day, 2 days a week) to go through the materials. It may be worth noting that I didn't time myself when I did the practices. On the weekend before the first attempt, I took GMAT prep 1 (700, Q49 V36 IR4) and prep 2 (720, Q50 V38 IR8). I wasn't entirely satisfied with the prep scores, but I anticipated some "magical moments" might happen on d-day.

Result of the first attempt
The test went more smoothly than I expected: I finished 10 mins earlier for Q, and 5 mins earlier for V. Yet it turned out that the GMAT prep score was quite predictive of the score of my first attempt (710, Q50 V36). Apparently I f* up with my SC - according to ESR, percentile rankings of sub-sections were CR 98th, RC 85th, and SC 46th. See verbal ESR as below:


Preparation for the second attempt
After the first attempt, I thought the strategy to improve was obvious: improve my SC. With that in mind, I revisited the MGMAT SC guide, but this time more thoroughly. I also reviewed the SC questions in OG and OV, and made less error compared to my first time of practice.

Additionally, I bought MGMAT CAT tests and took all 6 of them:
1 (640, Q42 V36)
2 (670, Q46 V35)
3 (640, Q39 V38)
4 (660, Q44 V36)
5 (680, Q44 V38)
6 (680, Q45 V37)

It took me 1 month (~8 hrs/day, 2 days a week) for the preparation. Just before the test, I retook GMAT prep 1 and scored 740 (Q49 V41).

Result of the second attempt
I was completely shocked at the test center when I saw my score: 690 (Q49 V34). I did feel a bit rushed for both Q and V sections, since I concluded from my first attempt that I wrote the test slightly too fast and may have erred some questions because of that. Surprisingly, this time I f* up my CR - CR 39th, RC 80th, and SC 77th. Apparently I allocated more time on SC and less time on CR this time. My hypothesis is that given the enough time (like avg. 2 mins/question) on each question, I might be able to answer more verbal questions correctly. Verbal ESR as below:


Questions
So, given the situation here, what do you think my problems/weaknesses are? How would you suggest me to prepare for my next (and hopefully the last) attempt targeting a 750+? What are the areas I should work on, and how I should approach it? Any recommended materials apart from the ones I have gone through?

Any suggestions are highly appreciated!