Sleepless night, scored below expectations = 640 (q40 v38)

Thank you so much for your answer! I cannot even explain the level of anxiety I endured the night before the exam and right before I entered testing room. It completely got me burned out. I believe that even though my last score on verbal on GMAT prep (45) was inflated, I still think that 38 was probably a bit lower than what I can do. Naturally, I could be wrong.

To shed some light on how exactly I felt throughout the test, my first quant problem was "A had 1\2 as much money as B while B had 20 more dollars than C. Together they have XYY dollars. How much does B have?" And I managed to mess up that problem, which is, you will agree, easy. When I got my first sentence correction problem I did not know what I was reading. It was the weirdest feeling ever. That is also how I felt throughout most of the verbal section but I think I managed to recover a bit and pick it up towards the end especially throughout the RC section (there was one short passage, two long passages, and one short scientific passage in the end) - It seems quite solid difficulty. If I got 40 on verbal I would be content but good overall score won't show up without good quant (to be safe I need minimum 48) regardless of 38 or 40 on verbal.

The biggest problem is, I am not sure when to take the test and how to gauge my quant level. I kind of lost confidence here