Hi luigi.roza,
Your Official 550 is in range of your recent practice score AND your scores from 3 months ago. This means that you're remarkably consistent - you do certain things consistently well, but you also make certain consistent mistakes. Since you weren't able to significantly improve any of the little mistakes that you've been making, investing in some new materials (so that you can learn and practice some new Tactics) is likely a good idea.
1) What were your Quant and Verbal Scaled Scores on this Official GMAT?
2) Have you scheduled your next Official Test Date yet (and if so, then what date is it?)?
GMAT assassins aren't born, they're made,
Rich