We'd be happy to help. Just be aware that 3 weeks to increase from 610 to 680/690 is...ambitious. Most people would not be able to achieve that kind of score increase in that length of time.
I also wouldn't necessarily
expect to score higher on quant on the real thing. It's good that you score better on GMATPrep. I've still talked to a lot of students whose quant scores are close to their scores on our tests than on GMATPrep.
Others, of course, do have real test scores closer to their GMATPrep scores, so let's hope that's true in your case. But be prepared.
The number incorrect doesn't tell us very much about your performance on the test - the test score is not based on that metric. I'd recommend that you learn a bit more about how the scoring works and what implications that has for how you take the test. Start here:
https://www.manhattangmat.com/blog/inde ... lly-tests/Follow that up with the Scoring section of our free e-book The GMAT Uncovered (there's a copy in your MGMAT student center account already!).
Next, read this article:
http://www.manhattangmat.com/blog/index ... -the-gmat/Then, use the below to analyze your most recent MGMAT CAT (this should take you a minimum of 1 hour):
http://tinyurl.com/analyzeyourcatsBased on all of that, figure out your strengths and weaknesses as well as what you think you should do. (Focus on Bucket #2. You'll understand what that means when you read the last article.) Then come back here and tell us; we'll tell you whether we agree and advise you further. (Note: do share an analysis with us, not just the raw data. Part of getting better is developing your ability to analyze your results - figure out what they mean and what you think you should do about them!)
Please also let us know what materials you have to study.