Creative self-doubt

I'm currently wading my way through a creative writing course. It's made up of two parts; non-fiction and fiction. To be honest, I'm more interested in the fiction part but, the course is set up to do the non-fiction first and that's the way I've decided to tackle it too.

I recently sent my latest assignment off to my tutor for assessment. I hadn't been overly inspired doing it and it had really taken me far too long to get finished. Today I received the marked assignment and my tutors' comments. She was very happy with the work I'd done and actually told me how well written one of the pieces was. So how come I have so much self-doubt over my own abilities to write? Why do I put the assignments off until the only thing I can think about is the piece of work waiting for me on my computer and I feel guilty for not having done it sooner?

I enjoy writing and researching new topics, it's a great way of finding out new information but I can't understand why I don't believe more in the work that I produce. Is it normal for a 'newbie' writer to be overly critical with their own work? All of my assignment pieces have been well received so, why do I think that my tutor sees something that I don't?

I've started on my new assignment to continue with the course, but again, it's not a subject that really enthuses me. Perhaps I should just take it as another piece of writing practice and get on with it. I think that maybe the problem is that I don't want to do an average piece of work and do it just for the sake of it, I want to produce something of a decent standard. Is it normal to have such doubts and question our own creativity?

Hope that you all had a great weekend and that Monday has started with the creative juices flowing nicely!

Hasta pronto!