What company's CAT did you take? Sometimes they are not very accurate.
I don't think there is any difference in what types of problems you get wrong, just what difficulty they are. If you missed questions early it may be possible that you got sent into the easier buckets of problems which caused you score to suffer overall. Only missing 11 problems is very good no matter what though (as long as they weren't 11 in a row or something) and with that long string of correct answers I believe the score should have been higher.
If you are having trouble with RC I would recommend
GMAT Fiction, I think you have a good shot of a very strong verbal score. Good luck!