Hey Jo, this is a great short story. You've created a great character arc and given Carolyn a lot of depth with a misconception that leads her to make decisions that get her into trouble. I was immediately immersed in her story and read straight to the end.
It does need some more editing, though. You tell us how Carolyn is feeling instead of showing us and a lot of Caroyln's back story could be inferred or spread out throughout the story instead of a big block of info dump. I've taken a stab at the beginning to show you what I mean. I hope this helps!
“Maybe I should run away," Carolyn said, brushing snow off her sore butt. "This ski trip is the last straw!" She stared across at the steeper slopes where the rest of her family gracefully shushed and slalomed, while she was stuck here on the bunny hill. Carolyn snorted. Baby hill was more like it.
Her mother, Ellen, grinned and called out something Carolyn couldn't hear, and her older brothers and sisters laughed in response. She blinked away tears. "I guess they are just as happy without me.” But she didn’t blame Mom, it was only natural she wanted to be with her real children, and not her.
"They wouldn't even miss me if I did run away," she said, her shoulders slumping. In the past three months, she must have thought about running away from home at least a hundred times.
She shot a dark look at the tall, handsome man who came skiing to a showy halt beside her pretty mother. It hadn't always been this way, when dad was alive things had been different.
Three years ago when she was six, and finally starting to trust the family that had adopted her, a drunk driver ran a red light and smashed into the car her dad was driving.
Even now, tears sprang to her eyes when she remembered him. She was his special pet, and it always amazed her that none of her siblings seemed to mind.
"Come on squirt." He would call, as he swung her up, up, up, to sit on his broad shoulders. "Let's go...” for a walk... or to the park... or wherever else she might enjoy.
Carolyn blinked back the tears. She had been certain the family would send her packing after the funeral, and it was over a year before her heart stopped pounding every time someone came to the door. Of course, she didn't mention it to anyone. Why give people ideas that might not have occurred to them yet!