Hi CKG,
Based on the information that you've provided, there are a couple of things that stand out:
1) Both of your Official GMAT scores are 'in range' of 620. GMAC has publicly stated that the Official Score is within +-30 points of actual ability, so these scores seem to support the idea that you handled both of your Official GMATs in the SAME general way (you did the same things correctly both times and you made the same mistakes both times). Even after 3+ months of extra study, you did not make the necessary adjustments to how you "see" (and respond to) the GMAT to score higher.
2) The bulk of your practice resources for your second attempt seem to focus on a high volume of practice questions (without necessarily learning any new tactics). Working on 100s (or even 1000s) of questions in the same general way (as before) is NOT the best approach to gaining a big score improvement.
To hit your score goals, you have to change your tactics. Since you've now been studying for some time, you've likely developed some 'bad habits' that will take time (and willpower) to change. Thankfully, there are resources that can help you to do so.
When are you planning to apply to Business School?
Have you scheduled your next Official GMAT yet (and if so, then what is the date?)?
GMAT assassins aren't born, they're made,
Rich