Yeah, it's true.
Published, unpublished, untried, tried, experienced, inexperienced, pros, beginners.
WE ARE ALL INSECURE.
One of my best friends told me the other day, "I'm in that stage where I feel like no one is going to like my writing," when she's one of the best I know! Another told me, "I'm thinking about self-publishing a novella, because I want to introduce the world of my novel before I actually release it." For another, "I world-build too much; and I don't have the writing to compensate for it."
We all have our fair share of problems. The thing is, we CANNOT let this insecurity overtake us. It's for this reason Alex J. Cavanaugh started the Insecure Writers' Support Group (that I really wish I could re-join), and it's one of the most effective methods I've seen of helping insecure writers.
In my opinion, it's okay to be irrational if you're feeling insecure. Take a moment to imagine your book becoming a movie one day. Imagine the great reviews you're going to get. Get into a mindset that a majority of people are going to love your work (but don't let this become a permanent thought). Do what you need to do to get out of your rut, but don't let it go to your head. Confide in a friend. (Join the IWSG!)
Sometimes I think all writers, and other people who have similar work, need a reminder: you're not the only one feeling this way. There are others out there just like you, and you can go find them and encourage each other. Not only will it help them, but you'll feel better about yourself.
So I say this to you now: We are insecure. I'm insecure. So when you're feeling that way, seek someone out. You're sure to find someone with an open ear or a shoulder to lean on!