Hi kmb561,
GMAC has publicly stated that the Official Score that you earn on Test Day is within +/- 30 points of actual ability. While there were some slight 'swings' in the Quant and Verbal Scaled Scores of all of your prior Exams (including the 660 on the Official GMAT), these results show that you you essentially performed the same each time (about 660 +/- a few points). Based on what you describe about this 610, your Scaled Scores were approximately Q35/V38 - meaning that your Verbal was consistent with your prior performances, but you had a significant drop in your Quant.
Based on your prior Quant Scores (including the Q45 on your 1st Official GMAT), you tend to perform really well on most of the 'math' questions that you face, but you would occasionally make some little mistakes and you missed out on LOTS of 'strategy-based' points. With a Q35, you would have made LOTS of little mistakes throughout the Exam, so there's some question as to how you approached that section this time. Did you guess on a bunch of questions? Did you do a lot of work "in your head" (instead of taking the proper notes)? How thorough were you when you worked on DS questions? Unfortunately, we don't have the necessary data to answer these questions.
The missing points that you're after can all be gained in the Quant section. In addition, since you're interested in applying to Top10 Schools, it's worth noting that many Business Schools view an Applicant's Quant Scaled Score as an indicator of how that Applicant might handle the 'academic side' of the Program. Thus, the higher you can get your Quant Scaled Score, the better you might look. Given your score goal and needs, I suspect that you will need another 1-2 months of consistent, guided study - AND you will need to focus on learning and practicing the proper Quant Tactics.
Based on everything that you've described, I think that you would find the EMPOWERgmat Quant Score Booster to be quite helpful. Most of our clients complete that Study Plan in under a month, so the time commitment wouldn't be too intense. We have a variety of free resources on our site (
www.empowergmat.com), so you can 'test out' the Course before setting up an account.
If you have any additional questions, then you can feel free to contact me directly.
GMAT assassins aren't born, they're made,
Rich