Hi Chinmay1998,
The scoring algorithm on the Official GMAT is far more complicated than most people realize. Since that algorithm is proprietary, no GMAT company has an exact match for it, thus CAT scores can vary a bit based on the 'biases' involved in their respective designs. The most realistic CATs available are the 6 from GMAC (the 2 free CATs, and each of the 2 that come with Exam Pack 1 and Exam Pack 2), but the CATs from Kaplan,
MGMAT and Veritas are all 'close enough' to the real thing that they will provide you with a relatively realistic score assessment (assuming that you correctly take the CAT in a realistic fashion). The one Official CAT that you took resulted in a 690, so if you took that CAT in a realistic fashion, then that result is likely the most accurate one of the CATs that you listed. That having been said, there are a variety of factors that can influence your performance on a CAT/mock, including the time of day that you take your Exams, whether you take the full Exam or not, the number of lucky guesses and/or silly mistakes you make, etc. - meaning that your current 'ability level' might be higher or lower than that Score suggests.
In a prior post, you stated that you were planning to take the Official GMAT around October 15th. Is that still your plan? If not, then when is your Official Test Date?
GMAT assassins aren't born, they're made,
Rich