Hi PI0628,
Many Test Takers lead busy lives, so you're not alone in that regard. That having been said, the amount of time that you'll be able to consistently commit to your studies sounds a bit 'limited' - and that could influence how quickly you improve (and ultimately how high you might be able to score on the Official GMAT). Thankfully, the Round 1 application deadlines are several months after your current Test Date (June 6th) - so you could potentially use that extra time (if needed) to continue to study and improve.
Raising a 450 to a 600+ will likely take at least another 3 months of consistent, guided study - and you'll have to make significant improvements to how you handle BOTH the Quant and Verbal sections. To be efficient with your time, you would likely find it beneficial to invest in an additional GMAT Course (either Guided Self-Study or instructor-led). Most GMAT Companies offer some type of free materials (practice problems, Trial Accounts, videos, etc.) that you can use to 'test out' a product before you buy it. We have a variety of those resources at our website (
www.empowergmat.com). I suggest that you take advantage of all of them then choose the one that best matches your personality, timeline and budget.
If you have any additional questions, then you can feel free to contact me directly.
GMAT assassins aren't born, they're made,
Rich