Hey Sangeeta,

Congratulations on your consistency-at-700! That should give you great confidence heading into the test.

You won't find a test that is more accurately-scored than the GMAT Prep tests, as any other test out there needs to approximate both the scoring algorithm of the GMAT and the difficulty levels of the questions. Other tests are pretty good about getting you an idea of your scoring range, but you probably have to consider that you could very well be 30 points or so either way.

What all of these practice tests are great at, however, is helping you to determine how you're pacing yourself on test day, which mistakes you're commonly making, which concept areas you may need to emphasize to improve upon, etc. They're terrific at helping you determine how to improve, so I'd recommend that you focus your energies on that. Have you learned anything about common errors / pacing pitfalls / tricky concepts for you from your 3 tests? If you can work on those, you'll have a much better chance of minimizing your mistakes and maximizing your potential on the test.

I wouldn't worry too much about something like "I want to score 700 but my latest practice test was 680" just the same way that I wouldn't put any stock into "I want to score 700 and my last test was 730 so I've got it in the bag!". If you know that your scoring range is around your goal and that you've taken steps to improve that score, that should be the confidence you need to sit for the exam.