Frustrated

I am currently working on a short story about two sisters who hate each other and have magical powers. I don't know if it is any good, or if I will continue the story into a novel. At the moment, I quite like my two characters, so I'll see where it goes.
This is what I've been trying to do for the past few months - just play around with characters and settings, trying to find a voice, a story, a protagonist that interests me. So far I've come up with several short pieces, none of which are completed, and I am longing to write a novel again. It's like when you break up with a long term boyfriend - soon after the break-up, you don't want to go on dates again and get to know someone from scratch. You want that shared intimacy, the secrets, the safe comfort that comes with prolonged knowledge. At the minute I want to jump ahead to the novel part, in spite of not having a story, a plot, an idea even about what to write. Which is why I'm trying to write short pieces. Even though it's frustrating the crap out of me. Can't run before you can walk, as the adage goes.