GMAT jitters?

Hello Everyone,

I just took the GMAT and scored a disappointing 650 - Q-47, V-33. This was my second test and on my first test I scored a 640 Q-45 and V-34. On my first test, I only studied Quant so the low verbal score was expected. I was scoring about 650 on my CAT exams so a 640 was not an unexpected score. After the test, I committed myself for 4 months and studied Verbal, specifically SC like a mad man. My SC was holding me back, on my first exam my CR and RC were 40 and 38 respectively while my SC was a 28 according to the enhanced scoring report. Even though I am a native English speaker, grammar was never my strong point as I never learned the proper rules. After learning these rules, I was scoring a respectable 35-38 on SC in my CAT exams, and around a 38-40 on the overall Verbal section. I noticed my strong points were CR and RC as I only missed a question or two on the practice tests. My last two GMAT prep test were 700's so I was confident that I could hit around that mark going into the test.

Test day came and I was nervous! I gave myself plenty of time to sleep but I woke up early and couldn't go back to sleep, I was filled with too much adrenaline. During the test, the Quant felt much harder than usual, but still reasonable. I was scoring a 47-49 in my practice Quant and I ended up with a 47, which I am content with. Perhaps if luck was on my side, I could score a 48 or 49 but a 47 was still respectable. Then came Verbal, which turned out to be a disaster. I typically do not have issues with timing so I do not look at the clock very often. However, after Question 16 I checked the time and realized I was about 7 minutes behind. I freaked out and tried doing my best to catch up. I am not sure which questions slowed me down, probably a difficult CR, but I should have had the discipline to skip or guess and move on. I was heartbroken when I saw I scored a V 33. I just got my enhanced score report and my results for Verbal surprised me. I scored a 41 on SC and a 28 on both CR and RC. I attribute this to nervousness and speeding up in order to make up for lost time.

Now my question to experienced GMAT tutors/everyone, what can I do to calm my nerves and ensure that this doesn't happen again. I want to retake the GMAT soon because I feel like my knowledge and skills are much better than what I scored and that my RC and CR scores were a fluke (hopefully the SC score isn't a fluke ) My plan moving forward is to redo some of my CAT's and focus on Verbal timing. Any advice would be appreciated!