Am I commitment phobic when it comes to novels?

I've been thinking about the novel I'm supposed to be writing for my MA in Creative Writing at Manchester Metropolitan University. I say 'supposed to be' because for the last few weeks I've been writing a lot of short stories and flash fiction, but no novel. I can't say I'm blocked, quite the opposite - I'm writing more than ever and I've been asked a lot why I look so glowing. But the novel has been resting. The last time I worked on it I realised that every time I write it for a period of time and then leave it, the next time I come back to it I sound different. As if the protagonist has multiple personalities. Which might be the solution. You might say, don't leave it, keep writing it every day. But that's the thing - I write and then I feel as if I have emptied my tank of thoughts and sentences and I have to leave it while I re-fill.
With my self-imposed One Story A Day challenge I don't feel the need to not write. I like the freedom of short stories, so that must make me commitment phobic when it comes to novels. To make matters even more complicated, I've been avoiding reading novels too. I just don't want to commit. What if that writer's style influences my thoughts too much! And now the guilt feelings come flooding in: does that all make me a bad person? A bad reader? A bad writer?!
It is as if being just a short story writer - at least for now - makes us somehow worse than 'real writers' - the novel writers. The fear that publishers would not want to take me on without a promise of the real thing in the future. That writing short stories is just a preliminary step, sort of like being a trainee writer. That's quite similar to relationships, I think. If you only have flings and one night stands, society would generally think worse of you than if you are in a committed relationship. And if I am in a commited long term relationship (engaged, as it is), then why can't I commit to a novel? And should I?
In the meantime, I've been reading short stories and my favourite for this morning is World Enough and Time by Linda Mccullough Moore (The Sun Magazine).