Hi Dp152,
The process of taking (and reviewing) a CAT requires a significant amount of energy and effort - and takes time to 'recover' from. This is one of the reasons why you typically shouldn't take more than 1 CAT per week - and your last CAT should be taken about 1 week before Test Day. From what you describe, you took 6 CATs in 2 weeks - including one just two days before your Official GMAT. Considering the fact that you also had trouble sleeping the night before your Exam, there's a good chance that you experienced some 'burn out' on Test Day - and it sounds as though you were not at your best.
Thus, it's certainly possible that you were just too tired when you took the Official GMAT. That having been said, there could be other factors in your performance, so I'd like to know a bit more about how you took your CATs:
1) Did you take the ENTIRE CAT each time (including the Essay and IR sections)?
2) Which CATs did you take them at home and what was the other location you mentioned for your other CATs?
3) What time did you take 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? Had you seen any of the questions BEFORE (re: on a prior CAT, in an online forum or in a practice set)?
GMAT assassins aren't born, they're made,
Rich