Hey Maus,
I'm sorry to hear how frustrating your recent study experiences have been! It's good to vent, though - I love that a community like this exists for studiers so that you don't have to feel alone and so that you can get some advice.
I'm really happy to hear you say this, though:
i guess its time to really change my quant study methods
I couldn't agree more - if you're working hard enough to make yourself sick-enough-to-miss-work, you're doing it wrong...regardless of your score. My guess is that you're pouring tons of hours in to "doing problems", "reading flashcards", and "studying books". None of which is an awful pursuit, but they're much more focused on "doing" than on "learning". And what you should really focus on is learning.
I'd recommend:
1) Stop memorizing rules and start asking why they're true. For example, x^0 = 1. And you can memorize that, but why is it so?
Well, there are a couple ways to represent x^1 * x^-1.
You could say that, because multiplying the same base to two different exponents is the same as adding the exponents together, then it's: x^(1-1) = x^0
You could also say that, because anything to a negative exponent is the same as dividing 1 by the base to that positive exponent, that: x^1 * x^-1 = x^1 * 1/x^1. So then you'd have x^1 / x^1 = 1.
And so you can prove that x^0 = 1.
What's great about proving it is that now you OWN it - you're not hoping to remember it...it's just part of what you know to be true, and even if you blank on it you could always go back and prove it again because you've been there.
2) Make your study sessions thematic
If you're just "doing problems" you may not be learning much from that, as GMAT problems can be quite varied in the types of skills they test, the processes required to do them well, etc. Have some specific goals each time out, such as:
-really understand and appreciate the Data Sufficiency format (and then slowly work through DS problems noting the subtlety in wording)
-become quicker with algebra problems (and then do timed drills)
-learn to love probability (and then work through some probability guides mastering small concepts - coin flips - up to harder problems - multiple sequences)
If you can leave a 2-hour session at the library saying "I feel like I'm much quicker at recognizing exponent rules now" and not just "I just did 40 problems", you'll feel a lot better about that time and you'll have a better idea of what you need to do next.
3) Slow down
This corresponds to the above tips, too, but remember that Rome wasn't built in a day (side note - I took a Roman ruins tour last summer and asked the guide at least a dozen times "what day was all this built?" The joke quickly got old to everyone but me) and you don't need to master the GMAT all at once. Embrace the stuff you don't fully get yet and try to understand it, not just shortcut it. Think it through and try to replicate it a few times with different numbers or a different question. I think often people rush through their studies trying to do a lot of things quickly, but slow and steady wins the race - let yourself win a few battles and pat yourself on the back for becoming a lot more comfortable with something like long division or prime factorization. At this point I really think you just need to feel success, but you're probably not letting yourself enjoy the little victories because you're so worried about everything else.
4) Don't rely on anyone's explanation but your own
I love the folks at GMAC and I thoroughly respect and admire GMAT questions and the way they're written. But OG solutions are simply not helpful in most cases. And more often than not neither are the solutions you'll read from any of the test prep companies. Really good solutions are hard to write, take a lot of time to write, and take up a lot of space...most books just won't have great solutions in them. ESPECIALLY because solutions really only give you one way to do it, in one set of words. They're written precisely the way that one person thinks, but not necessarily the way that you think. As a teacher, I know that I need to teach using what a student is already thinking - I can't force someone to relearn the way that I think.
So with GMAT practice questions, you have to try to make the answer make sense to you. I've worked with a lot of students who try to memorize Official Guide solutions and think that way, or who will say things like "I looked at it one way and I was one silly mistake from getting it right, but this book says to think this way...". If your way is even close, you can tweak it to be right, and that's the most effective way because it's in your words and style. There's no one way to solve any of these questions, and each way has dozens of ways that it can be described. THINK your way through the problems...don't try to learn in someone else's words. For one, you're much more likely to remember something if you put it in your own words; more importantly, GMAT problems are never exactly teh same, so you need to train yourself to THINK and not just to remember.
I'm really happy to hear that you know you need to change your study methods. Honestly, the above tips will not just make your study better and more effective, it should make it more fun. You have plenty of time to improve here!
I'm definitely trying to change the way in which I "learn". I've actually cut down the amount of problems im doing each day and trying to really focus on figuring out WHY a problem is right or wrong. I just started studying this way so I'm not really sure if its paid off yet, but hopefully it's a step in the right direction. So far, it's been pretty slow but making that effort - here I come, quant - get out of my way! 
