Relax Neha,
GMAT is a bit like the one day cricket match (I think you'll get the point assuming you're from India)
you can only practise as much..............If you have certain weak areas that havent improved much, one week will not make too much of a difference.
I'd suggest you just work hard on reviewing concepts, reviewing the common mistakes you have been making all this while.
Finally, try to stay calm on the test day and take the test as it comes. Dont stress too much.
I stressed myself out a couple of days before the test and didnt do as well as I know I could have.
GMAT is like one day cricket, as long as you have the basics in place, all you gotta do out there is believe in yourself and play every ball as it comes.
If you get scoped out facing a real fast bowler even before he bowls his first ball, you'll not score much...................I think you get the point