Hi svishnu1994gmailcom,
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 likely what happened here. By skipping sections and taking the CAT at home you have not properly 'mirrored' what you'll experience when you take the Official GMAT. From now on, you should plan to take your CATs in a more realistic fashion (by taking the FULL CAT - with the Essay and IR sections, away from your home, at the same time of day as your Official GMAT, etc.).
You didn't answer all of my questions - and those additional answers will impact the ultimate advice that I'll end up giving you. Given your score goal, you should plan for a longer study period.
GMAT assassins aren't born, they're made,
Rich