What was the breakdown of your quant and verbal scores on your practice tests? You had one MGMAT at 690, while the other scores were lower - what was the difference on that test? Why was it higher?
Your practice test scores were in the same general range as your real test scores, but I need to know the subscores as well to see how things were changing. Also, you said the 620 score wasn't one that you want to count because the test was interrupted... but that was also closest to your real test score, so there may be important things to learn from that test.
Use this article to analyze your recent MGMAT practice tests:http://www.manhattangmat.com/blog/index ... ice-tests/
Then come back here and share your analysis with us. Note: don't just give us the raw data. Tell us your analysis - what you think it means. You have to learn how to analyze your own performance and progress. Otherwise, you're going to continue to be frustrated adn feel like you're not making enough progress.
Next, you talk about "strike rates" on practice questions, but percentage correct means almost nothing in the absence of timing data - which tells me that you don't know enough yet about how the GMAT works and how the test is scored. Read this:http://www.manhattangmat.com/blog/index ... to-win-it/
And you may also want to read the Scoring section of our free e-book The GMAT Uncovered (it's in your student center).
Next, if you have any timing problems (and you probably do - we all do!), read this and start doing what it says:http://www.manhattangmat.com/blog/index ... anagement/
You're right that we only have a couple of months before the test changes. Given that you want a 690+ and that you're not sure where you're going wrong in your studying, there's a decent chance that you will not be ready to get that goal score before the test changes. The good news, though, is that the IR section is not going to be super important for at least the first year of admissions. So if you do have to take that section, you'll study for it to get a "good enough" score, but you'll still focus mostly on quant and verbal.