It's strange - multiple actresses are showing up lately that seem to look like Kristen Stewart, but then when I look for images, they look nothing like her. Finally, my friend Alison pointed me towards Take Me Home Tonight's Teresa Palmer. She's got the Bella Swan pointy chin and nostril flare, and (at least in these pictures) their mouths are identical. Also, having floppy hair goes a long way in a Kristen-alike challenge.
I think that the issue with finding lookalikes who ACTUALLY look like K Stew is that her eyes can't be matched. I don't want to say this, but maybe she's got really special eyes? I didn't want to say that. I take it back.
PS the other KStew-nonalike is Amber Heard from Pineapple Express - in the movie she reminds me so much of Kristen Stewart, but in my google image searches she ends up looking more like ScarJo. More on this later.