Hi sandeeepsharma,
The OG books are great sources for practice questions, but just doing 'book questions' makes it difficult to determine how well you are actually prepared for the Official GMAT.
Have you taken any FULL-LENGTH CATs (including the Essay and IR sections)? If so, then how have you scored? What were your Quant and Verbal Scaled Scores? THOSE scores provide a more realistic assessment of your skills because they are measured in context of how you handle the FULL GMAT. If you can't perform at high level throughout a FULL CAT, then the solution(s) to your problem involve more than just doing practice questions.
GMAT assassins aren't born, they're made,
Rich