Hi zepedac,
Unfortunately, no book can properly measure your skills in the way that you're hoping the OG will. The OG books are great sources for practice questions, but they're not designed to teach you Tactics, patterns or the little 'secrets' behind the GMAT - for those, you'll need Course-oriented materials.
Since it sounds like you've done some studying, then it would be a good idea to take a FULL-LENGTH practice CAT Test; you can download 2 for free from
www.mba.com (and they come with some additional practice materials). That score will give us a good sense of your natural strengths and weaknesses and will help provide a basis for comparison as you continue to study. A FULL CAT takes about 4 hours to complete, so make sure that you've set aside enough time to take it in one sitting. Once you have those scores, you should report back here and we can talk through your study plan.
1) When are you planning to take the GMAT?
2) When are you planning to apply to Business School?
GMAT assassins aren't born, they're made,
Rich