Aww don't feel bad! I know how you feel, when i first got oreo he was SO tiny and he's black and so is my carpet (well it's really dark dark blue) and he blended in, believe me we stepped on him SO many times
i thought i broke him! but luckily I didn't
As long as she can run fine now, she's alright. It's a good thing if your going to call the vet in themorning, just to be safe. Better be safe than sorry.. although i don't think she's hurt anymore. good luck and best wishes!