You mentioned that you took a Manhattan Review class and that you used "Manhattan official guides." Do you mean that you used Manhattan Review books, or do you mean that you used Manhattan GMAT books? I want to know what resources you have available. (For others who might be confused, Manhattan Review is a different company.)
So:
1. you took a class with Manhattan Review
2. you took a long break after the class and forgot a lot during that time
3. when you resumed studying, you only had about 6 weeks.
4. you had a lot of anxiety during the test, especially on the verbal.
5. you also struggle with timing / speed; this is usually only on verbal, but on the real test, you also had a problem on the quant.
First, your actual ability is certainly better than your test score. The fact that you had to guess on so many questions at the end of each section really brought your score down. So, one thing we need to fix is this timing issue.
This test is not just testing you on whether you know the material and can answer the questions. It's also testing you on whether you can set priorities and manage your time appropriately (as any good businessperson should know how to do!). Think about your average workday - sometimes there are things you have to leave till tomorrow or next week, right? Sometimes there are things you have to give to somebody else or say you can't do.
The same thing happens on the GMAT. No matter how good you get, you will still have to guess on something like 5 to 7 questions in the math section. You don't want to be forced into making those guesses in a row at the end of the section, so choose the 5-7 hardest questions AS YOU SEE THEM throughout the section. Remind yourself that you CANNOT get to the point where you can answer everything given to you in 2 min - that's just not how the test works. You have to let those go.
Use the below article to analyze a recent MGMAT practice test (if you haven't taken one in the last few weeks, take another
under full official conditions).
http://www.beatthegmat.com/a/2009/09/23/evaluating-your-practice-testsAnswer these questions:
- if you spent too much time, why? specifically, which part of the problem and what caused you to spend the extra time? did that extra time help? did that extra time hurt on a later problem? (if you spent more than 30sec over, the answer is yes, even if you got this problem right) how did that extra time hurt? specifically, where did you then not have enough time?
- if you spent too little time, why? were you rushing b/c you were behind? why were you behind; on which ones did you spend too much time? or did you think the problem was easy and you didn't need that much time? how often did you make mistakes on those "easy" problems on which you felt you didn't need full time? (On problems like that, you should make almost no mistakes - 95%+ accuracy. So if it's anything lower than that, you're hurting yourself by choosing to go fast when you think a problem is really easy.)
I think you would also benefit from a timing exercise: learning about how long one minute is without looking at a watch or stopwatch. If you don't have one already, buy yourself a stopwatch with lap timing capability. When you go to do a set of problems, start the stopwatch but turn it over so you can't see the time. Every time you think one minute has gone by, push the lap button. When you're done, see how good you were - and whether you tend to over or underestimate. Get yourself to the point where you're within 15 seconds either way on a regular basis (that is, you can generally predict between 45 sec and 1min 15 sec).
Now, how do you use that when doing problems? If you're not on track by one minute*, make an educated guess and move on. (The general idea is that if you're not on track by the halfway mark, you're unlikely to figure out what's holding you back AND have time to do the whole problem in the 1 min you have left.)
* For SC, 1min is well beyond the half-way mark (we're supposed to average about 1m15s here), but you can almost always eliminate at least some choices on SC in that timeframe. Once you've got that "I'm around the 1min mark and I'm struggling" feeling, go through any remaining choices ONCE more. Pick one. Move on.
Next, there are presumably some content areas in which you need improvement. The article above that discusses how to evaluate your practice tests will help you to identify what those are. You'll then need to use either your existing resources (books, etc) or new resources to help you fix whatever those problem areas are. (And you already have good ideas about some of your problem areas on the verbal side - so follow up on .)
Finally, I completely agree that you need to train your brain - your brain needs regular exercise to be able to perform at its peak on test day. Given your goal, you are going to need to commit to a regular program of study for several months - 5 to 6 days a week. Why did you take the "break" you took before? If it was due to procrastination / low motivation, then you may want to study with a friend, join a study group, or take another class to keep yourself on a steady schedule.
If you have our books, then you may also want to use our standard syllabus:
http://www.manhattangmat.com/freegmatlearningforum.cfmClick that link, then look in the top section ("Highlights") for "Official Manhattan GMAT Course Syllabus [pdf]"