Hi Elchin1994,
Before I can offer any suggestions, I'd like to know a bit more about how your studies so far.
When you took your CATs:
1) Did you take the ENTIRE CAT (including the Essay and IR sections)?
2) Did you take them at home?
3) Did you take them at the same time of day as your Official GMAT?
4) Did you ever do ANYTHING during your CATs that you couldn't do on Test Day (pause the CAT, skip sections, take longer breaks, etc.)?
5) Did you ever take a CAT more than once?
6) When did you take each of your two GMATs?
Raising your score 100+ points in 3 weeks may or may not be possible. Do you have the flexibility to push back your Test Date? The extra study time could greatly increase your chances of raising your scores.
GMAT assassins aren't born, they're made,
Rich