Hello!!

This is my third time for taking GMAT exam, but my scores are still horrible.

Fact
1st (Jul 2016) : V18 (I did not purchase Enhanced Score Report)
2nd (Jan 2017): V17 (15%)
- CR 6 (5%)
- RC 16 (17%)
- SC 23 (34%)
3rd (Feb 2018) : V17 (15%)
- CR 6 (5%)
- RC 28 (52%)
- SC 19 (22%)

I confessed that all times when I did the real exam, I felt panic, anxiety, and pressure. When the first questions was appeared on screen and I felt that I don't understand the argument or passage at all. With the light font on screen, long content on each paragraph or argument, I answered all questions with my instinct. Last time, I don't understand throughout the passage. I skip for last 2 passages to save my time and answered by taking a chance.

Anyway, when I did on the OG book, my accuracy rate is 70-80% on average.
RC - My reading speed is quite slow (15 mins for all passage with 5-6 questions with 80% accuracy rate). Anyway, I am pretty understand the flow and content of passage
CR - I can catch where the conclusion is and clearly understand how to attack the question. I am not familiar with the argument that used the difficult words and long argument and choices, giving me not clear understanding.
SC - I think my pitfalls are that I was careless on something easy.


So, I would like to know that
1) How could I improve my verbal score as in fact I can answer most OG questions correctly. I aimed at 30+
2) How I plan my study schedule. I plan to re-take the exam again on May.
3) How could I control my anxiety, my stress when I faced the passage which I don't understand or long argument on CR.

Background
I am non-English native speaker.

1st time : I have less prepared for my verbal. I prepared just SC and a little bit of CR.

2nd time : I work so hard on verbal. My materials are OG2017 and Verbal Review 2017. Anyway, I still am not understanding in some answer explanations. I did 6 mock exams from GMAC. My verbal score is 17-21.

3rd time : I took the best GMAT prep school in my country. I have felt more confident for this time because now I can answer most OG questions correctly even some questions are wrongly answered, I understood every solution explanations. But the nightmare was when I took a mock test. Unfortunately, I have a few of preparation time for taking mock test. I did mock once and the result is that V21. However, I did Global expert 3 times. My result was that V21, 28, and 32 --- too much overstate ?

Thank you very much