Hi ali123,
The extra information that you've provided is quite useful, as it helps to define what went wrong on Test Day. In real basic terms, you took your CATs in such a way that you were NOT properly training to face the Official GMAT - so you were not ready to face it on Test Day. Test Day is a rather specific 'event' - the details are specific and they matter, so you have to train as best as you can for all of them. The more realistic you can make your CATs, the more likely the score results are to be accurate. The more you deviate, the more "inflated" your scores can become - and that's what happened here. By taking your CATs in an inconsistent fashion - skipping sections, taking the CATs at home, taking them at different times of day, etc., you weren't properly training for the FULL GMAT 'experience.'
Thankfully, this is a relatively easy set of problems to fix. The big question now is "how long will it take you to properly get 'used to' taking the full GMAT?" You'll certainly need a new set of practice CATs to work with and you have to put in the necessary time to train your brain (and body) to take the FULL GMAT under realistic conditions. You might also need to invest in some new GMAT training materials.
1) When are you planning to apply to Business School?
2) How many hours can you commit to studying during a typical week?
GMAT assassins aren't born, they're made,
Rich