Hi Kate.li88,
From what you've described, you have a lot of potential study time - which is good. However, you have to be careful about confusing 'quantity' of study with 'quality' of study - and you have to be careful about not 'burning out' (as 50 hours of study each week would would be a LOT of studying). It's not clear whether you actually need a tutor or not, but working through a 'fixed class' schedule clearly didn't work for you, so you'll need a study plan that's a bit more flexible (and that can allow you to spend more/less time on individual subjects as needed). Given your needs, I still think that a GMAT Course of some type would be really beneficial. 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