Hi EuropaIo,
From what you've described, I'm sure that you've worked through lots of practice SCs, but it's not clear HOW you learned to work through them (your knowledge, Tactics, etc. of that subject). In addition, while you've self-defined SC as a potential area for improvement, it's not clear whether that's the only area that you need to work on or not. Have you purchased the Enhanced Score Report for your Official GMAT? While the ESR doesn't provide a lot of information, there are usually a few data points that we can use to define what went wrong (and what you should work on to score higher). If you purchase the ESR, then I'll be happy to analyze it for you.
Before I can offer you the specific advice that you’re looking for, it would help if you could provide a bit more information on how you've been studying and your goals:
Studies:
1) How long have you studied?
2) What study materials have you used so far?
3) How have you scored on EACH of your CATs (including the Quant and Verbal Scaled Scores for EACH)?
4) How did you score on the Official GMAT (including the Quant and Verbal Scaled Scores)?
Goals:
5) What is your goal score?
6) When are you planning to retake the GMAT?
7) When are you planning to apply to Business School?
8) What Schools are you planning to apply to?
GMAT assassins aren't born, they're made,
Rich