Let me suggest something a little bit counter intuitive. Since you have a defined goal of 550 (which is close to the average score) you just need to get a reasonable number of questions right. There is no need for you to fear missing some questions - you can miss 50% of the questions on the Quant and usually get the 50th percentile or greater. On the verbal side you can afford to miss lots of questions as well.
I have had more than one student with a similar goal of anything above 550. I am thinking of one particular student and the strategy we come up with was for him. He had a problem on the Quant with trying to do whatever question came up and so spent most of his time on questions that he struggled with (you can see how this would work, questions he was comfortable with did not take nearly as long). This made the test long, unpleasant and low-scoring. I told him that he had to "skip" - meaning quickly guess at - at least 5 questions on the quant section. Obviously these would be questions that he had no chance of getting correct within 3 minutes. I then told him to focus and not to rush when he found a question that he was confident in completing. The results were better than he could have hoped. This method allowed him to at least see most of the 37 questions and to choose which ones he was best at. Remember he only needed to get something like half of the questions right in order to reach his goal.
This changed the way that we studied as well. Instead of focusing on the types of questions he was not good at, we focused on those that he was pretty good at and worked to make those into real strengths that he could rely on on test day. By getting these question types down cold he had the confidence to make it happen on test day.
So that is something you might try...study the things that you are good at or can become good at and make these into things you can rely on under pressure. If there are question types that you are hopelessly bad at then these might be the questions that you guess at on test day.
And, hey, this might make your studying and even test day a little more enjoyable, not to mention successful.
