GMAT Strategy

I have been working for 5 years now and i think i got a serious test taking problem. I can concerntrate very well at home but not on the test day.
I have actually done several practice tests (Gmatprep) before the offcial test day. The lowest i got was 510 and the highest was 620. I was so confident on the test day and I felt so good after the quantitative part, but the verbal part was a disaster. I left 3 to 5 questions unattended. Of course, i got a very bad result that i almost wanted to kill myself
Does anyone know what is the penalty for the unanswered questions?
Does anyone know how to be calm on the test day?
I only need 500 to pass!!!!!!!!!! How can that be so tough!!! I have never felt that stupid and useless before....
Thanks guys.

The stress of the actual test can be huge. Do you maybe have test anxiety? Or did the verbal part just feel different than what you'd seen in practice?

Hi,
Well same problem is with me, have patience no one is perfect just practice more on that sections where you are week carry on, you will definitely get the success.