Hi gmat5ever.
The best move you can make to drive up your quant score is to find less strong areas in your quant skill set and make them stronger. So, far, with the type of preparation you have done, using the
OG, my take is that you have done mixed sets of quant questions. Now, to strengthen less strong areas, work on questions one type at a time.
For instance, if you are not strong in answering probability questions, focus on probability by itself. Learn all about the concepts that underlie how to answer probability questions, learn how to answer the questions accurately, and practice by answering dozens of such questions, until effective methods become your instincts.
Then move onto another type, such as overlapping sets questions, absolute value questions, or whatever other type you could be better at answering.
In two weeks, you could become MUCH better at answering ten types of questions, and by doing dozens of questions of each type one after the other, you will lock in your use of effective methods for answering them.
Meanwhile, take more practice tests over the next two weeks, both as a way of determining what types of questions to focus on in order to strengthen your less strong areas and to develop better timing. If you think about it, it's not that surprising that you would have some timing related stress the first time you took a practice GMAT. Imagine how much different you will feel in your third or fourth GMAT experience.
The
OG quant questions are, generally, not as difficult to get correct as some of the questions on the real test. So, to practice, you should find another source of questions. One possible way to get more questions would be to use a self-study course, which would provide you with many categorized questions of various difficulty levels.
When you are doing practice questions, do them slowly, focusing on getting them correct. 8/10 to 9/10 correct in practice may not be quite high enough a hit rate for scoring 50 - 51 in the quant section. Probably, you should slow down and seek to get 10/10 correct on some sets. Any question that you don't get right can be an indicator of a less strong area in your quant skill set. So, any time you don't get one, consider focusing on that type of question to build your skills.
When you take the test, focus on the question in front of you and seek to get it correct. Don't rush. Breathe deeply and seek to execute. One great way to reduce anxiety is to ignore anxiety and focus on the question in front of you. You can spend way more than two minutes on some questions, as you will likely answer some in way less than two minutes. For practice, you could take a practice test and see what happens if you barely worry about the time. Just seek to get right answers without worrying about the clock too much, and see how it goes. Even if you were to run out of time at the end of the quant section and were to have to guess on a few, you could still score 50 or even 51 on the quant section. The test will give you a higher score if you miss the last three quant questions than it will if you miss three closer to the middle of the section.
Finally, see the GMAT as a game of getting as many right answers as possible. By playing it like a game, you can make it fun for yourself, optimize your attitude, and maximize your score.