Hey Barely,
My friend, let me tell you right away: you are not the first nor the last person to be a casualty of their first few GMATs.
I know firsthand because on my first GMAT I got a 480.
You have to realize a couple things. The GMAT isn't a math test. The GMAT isn't a test measuring your verbal ability. It doesn't measure your intelligence or IQ and it certainly doesn't measure how well you will do in graduate school. The GMAT tests how well you can do the GMAT, period. Because of this, your training needs to be structured around this concept. Don't try to learn math, or verbal properties. Focus on learning how to destroy the GMAT.
This is why I am convinced that there are ONLY two effective ways to study for this test.
1) Answering timed question packets.
2) Doing timed tests.
Looking over math concepts, studying grammer concepts, reading about probability etc. is a waste of time. It doesn't test you. You may know how to do Work word problems, but when confronted with a tricky work word problem, do you freeze up and re-read the question multiple times or do you spring into action??? You must literally SPRING into action at every question!
On the GMAT, odds are you will not use half the knowledge you might acquire. What you need to practice is speed and reaction time. You can only do this by doing question after question on various subjects, and timing yourself.
You seem to need practice both in Quant and in Verbal. Structure your own practice packet that fits your needs. Your practice packet could be: 20 SC, 20 critical reasoning, 3 reading comprehension, 20 PS and 20 DS. These questions need to come from Official Guide 10 (the best, hands down) and
OG 11 (also good). Use Princeton, Kaplan and other sources sparingly as their question writers can be sloppy. Do the packet AT LEAST 5 times a week. Take a TIMED test once or twice a week, or more, to learn the scoring and the timing you need to get a good grade.
Above all, DON'T GIVE UP and stay hungry. You can and WILL succeed in business school. Don't let this test make you give up on your dreams.
Good luck bro. You can do it.