Killed by GMAT 530 (Q47 V17) Need help!

Hello guys!

I took GMAT today and I totally screwed up especially the verbal part. (GMAT 530 Q47 V17)
I think my poor score has something to with these factors: time management and stress. (Oh! my poor verbal, too.)
For the quantitative part, IMO the level of difficulty is pretty much the same as the gmatprep. I thought I did it quite ok
but it could be much better if I managed my time more efficiently. In the last five minutes, I still got about ten questions left. (I guess almost all of them)

For the verbal part, I totally screwed up. Generally, I am poor at verbal but today is the worst. I was stuck at the RC for a long long time.
I tried to read it and I was like OMG! I didn't get any of this. Real CR, SC for me too are much harder than the gmatprep. Although I tried to calm myself down, I knew my mind was already gone somewhere else. I spent quite a lot of time doing the first few questions. In the last ten minutes, I got 20 questions unanswered. I know this sucks and it shows how poor my time management is ... I had to guess half of the verbal part! I have never guessed so many as these in my entire life! So when I saw the score, I was not surprised. I knew it's gotta be like this since I guess half of the verbal part.

The thing is I'm gonna retake the test next month so I've got about a month to improve my verbal (also my quant). Any suggestions will be highly appreciated.
FYI, I took GMATprep four times and here are my score (kinda vary though): 600 (Q48,V25), 540 (Q45, V20), (reinstalled)640 (Q49,V28), (reinstalled)700 (Q50,V34)