First thing - don't compare your score to others on this site! Each person has his or her own capabilities and expectations.
I know how you feel. I bombed the test on my first attempt a couple weeks ago. I then took 1 full week off to rest my mind and rethink my strategy. Let me tell you, that time off helped me <b>extremely!</b> I am now back to my normal self, ready and motivated to beat the GMAT! As you have, I purchased the
OG 11th edition, and so far, am enjoying the book. While there is overlap, the explanations and format are 100% better than the 10th edition. The Q section is a little harder and I feel it is more representative of the current math on the GMAT. I've been more active on this board and I think it has helped as well. Everyone here has a great attitude and offer great advice.
My advice to you is take some time off and clear your mind. Then come back with a furious vengeance to conquer the test! Keep an
error log and go to town on your weak areas. Start with the basics and go from there. I aced all my math courses in undergrad (which unfortunately was 5+ years ago) but have since forgotten many of the basic math concepts out there so I'm going to do as many Q problems as I can every night; I try to do at least 20-30 math problems nightly and finish with 5 CRs, 10 SCs, and 1 RC passage. Of course I try to do more on weekends.
Hang in there and don't give up! People generally say to plan for 2-3 attempts before you get the score you want so if you think about it, we just took a "warm up" test