Trying to remember a story...

Just remembered a few details about a story I read a long time ago here, probably before I made an account. It was a "For Want of a Nail" - type AU. Same main cast, just in different roles and situations. I only remember half of them, though. I think the Sonic Rainboom either didn't happen or happened much differently. And the story went through the Nightmare Moon episodes, at least.

I think there was something about Rainbow getting seriously injured while she was young, to the point of being forced to live on the ground. Then....she invented...something. Some device, I think that would helps others like her? In any case, her invention took off, and Rainbow ended up with more money than she knew what to do with, so she sold the rights to her device, saved up some money for herself, for her parents, and then gave the rest to the government or something.

Fluttershy....ended up as an extremely strong flier. She might have helped teach remedial fliers or something, but I think she got her cutie mark helping to break up an extremely large and dangerous storm.

Twilight, I remember, was afraid of her own strength. I don't think Celestia was around to calm her from a magical surge caused by....the storm I mentioned, I think. Twilight...visits Sweet Apple Acres, at some point? Gets her cutie mark related to botany, maybe? Applejack's probably in Manehattan still. In any case, Twilight delivers a "World of Cardboard" speech to Nightmare Moon towards the end.

Anyone happen to know the title of this story? I searched for "For Want of a Nail" but didn't find what I was looking for. Figured I'd at least write this down before I forget.