Were they trying to make Chris 'SYMPATHETIC'? spoilers?
Almost every time she does something "bad" you look at her face afterwards and she seems to be thinking about what she had done. Maybe actually being "sorry" for doing something "wrong". I don't know, it might just be my perception.
After Chris is suspended and Sue Snell almost tells her to shove it you can see Chris thinking. Maybe what she did to Carrie was wrong, even if she first says "It's Carrie's fault".
Also before the "Blood Scene" Chris is really thinking about what she's doing and reconsidering hurting Carrie again. It's really Billy's taunting that puts Chris over enough to pull the rope.
Then later Billy tries to run down Carrie and Chris actually tries to stop him.
I might be going by the Original movie more that the Book, but Nancy Allen played Chris ruthless with no remorse what so ever. Allen was the opposite of TV Version it seems.