Hey guys, i have 2 thign to say to you:
First, neither 630 nor 640 are bad scores. Not at all! Keep that in mind.
Second, here are plent of topics here from people who had about your scores, and through some more study, exercises, and concetration at the test time, improved they score to +700.
So, my advice is: keep on studying, do plenty of prep tests, keep on posting your doubts here, because we have great ppl here to answer them, and don't ever lose your faith, cause you both will surely get your +700 score