Hi rediforking,
Many Test Takers use a variety of study materials, so there's nothing wrong with purchasing resources from different companies. Based on what you've described though, your prior studies were 'book heavy'; many Test Takers who study in that way end up getting 'stuck' at a particular scoring level. This might have happened to you (your CAT scores and Official Score are almost all in the low-600s). With a 740 score goal, you're going to have to make some significant adjustments to how you handle BOTH the Quant and Verbal sections, which means that you'll likely need to invest in some new non-book resources and learn/practice some new Tactics.
In regards to your CATs, you should try to take 'new' CATs each time (so you can avoid seeing repeat questions). The CAT in which you completed just 3 of the Quant questions could probably be reset/reused with minimal harm, as long as you complete the FULL CAT (including the Essay and IR sections). It sounds like you have plenty of practice CATs though, so you could 'bypass' this one CAT for now and come back to it later (if need be).
Based on everything that you’ve described, I think that you would find the EMPOWERgmat Total Score Booster to be quite helpful. Most of our clients complete that Study Plan in well under 2 months, so the time commitment should fit your schedule. We have a variety of free resources on our site (
www.empowergmat.com), so you can 'test out' the Course before setting up an Account.
If you have any additional questions, then you can feel free to contact me directly.
GMAT assassins aren't born, they're made,
Rich