Hey rockroars,
Nice work timing difficult problem sets - that will pay off!
Honestly, I don't think your performance is that bad...the latter half of the OG is known to be above average difficulty, and if you're more right than wrong you're probably looking at an above average (or so) score.
Now, what's absolutely crucial - go back to those mistakes and try to determine why you're getting them wrong. Data Sufficiency is a game...the more you can see how the questions are using your momentum against you the easier it is to recognize where the traps are coming from. So although this particular set may translate to something a little above average, learning from those mistakes and better understanding the game can catapult your score higher. Embrace the mistakes that you make in practice, because they're the gateway to success on the exam!