Here's my take on what possibly went wrong.
1. Over reliance on your Quant. You scored 45 in the retake, so clearly you in the 70 odd percentile level. Though it makes sense to push your Quant to 50 levels. It is much more wise to propel your verbal score. Should you decide to retake the exam and in my opinion you should, You should focus on your verbal completely.
2. There are few things that go wrong with Verbal for most people but it all boils down to one of the following three problems.
A. Content : Were you aware of all the question types, i.e for SC what are all the content areas, which is your strongest/weakest area, for example do you get a lot of Verb tense questions wrong? Did you do a focused study tailored for these weak areas in verbal? did you review all the possible CR questions types? What questions puzzle you the most?
Have you defined a clear strategy to attack SC/CR questions. For example for SC questions, I read the sentence slowly looking for errors moment i find an error i go to the options where the error is corrected and mark off the wrong ones and then i try and reach the right answer using POE.
For CR moment i see a lot of numbers in the question, I know this question will require making small calculation, If its a causation question then i know the possible right options.
Idea is to have a defined strategy to attack each questions. It just helps to have a method to the madness. Solving a SC question in under 1 minute and a CR question in 2 odd minutes can be quite a havoc.
For RC, i just try to calm myself before starting a RC and i don't rush in, i also tend to take notes if i feel that my mind is drifting or if the passage is tough. Answer RC question as you would answer CR questions.
B. Timing: Are you able to finish the section in time? Do you find yourself rushing through the last few questions, When i was preparing for my first GMAT attempt i noticed that i got very few questions wrong in the first 25-30 questions and then ended up messing the last few because i was always rushing in. The idea is to adhere to timing grids, if you think you are behind at a particular stage, then its better to guess a question in the middle than to guess a bunch of questions together at the end.
C. Stress Management: GMAT is a piece of cake for some and a never ending battle for others, its just the way it is, some of us just have a better foundation of math and verbal concepts than others, It just makes things difficult, NOT IMPOSSIBLE. If you go into your GMAT exam thinking that its a do-or-die situation then you are bound to rush into questions, moment you see that time ticker moving and you find yourself taking too much time to answer a question. You make that error.
I have found that every question i make an content or technique error is a question on which i took more than the allotted time (1 min SC, 2 CR, 7-8 min for a RC passage). Just relax, GMAT is just an indicator.
Now, here's why i think you should go in for the test the third time.
1. To increase your chances at your dream school : No its not as obvious as you think, you may or may not do better at your third attempt, However, by showing the courage and the zeal to take it up the third time is going to impress the Adcom.
2. Improve: Ever tried to do a question over and over? You get it wrong the first time, second time you get close to the right answer and then make a silly error, third time you nail it at the first go.. Fourth time.. you just remember the damn question, the solution and the answer.
GMAT works like that, its all about Patterns, all questions are merely a variation of a small set of question types. More you practice and more questions you solve, more patterns you will be able to recognize on the real test.
Good luck.
PS: Pardon the grammatical mistakes above.
