If you have not completed these then I recommend using the following tests:
1) GMATPrep Practice Tests 1 and 2 (Free from mba.com)
2) GMATPrep Exam Pack 1(Two additional full length CATs from mba.com)
3) GMATFocus set of three diagnostic tests from mba.com.
Free Video Explanations: OFFICIAL GUIDE FOR GMAT REVIEW 2015.