Goobers, your writing is great, but Linda suffers from the common problem of being "Too Super". Don't get me wrong - I love your stories. But for you to spin out a long story she needs a challenge, but because she's super your big challenge is developing a challenge.
I know you know all this stuff, but Linda is so together that makes it tricky. She needs some angst. I hate to suggest what you might consider, but in her case one idea is simply becoming so bored with the being super that she wills herself to be normal again. Maybe she wills herself to even forget she was super or think that being super was a dream or something and then you could slowly play out her desire to become super or maybe she is a real split personality: A super girl whose secret identity is even secret from her. Of course, I'm not claiming either of those ideas are unique, but you write well enough to execute something along those lines memorably.