Sherri, been there, done that and designed the t-shirt.

Having self-doubt is common, especially after having finished a project and trying to start a new one.

I went through the same thing about 3 weeks ago. What I did was gag that self doubt and look forward to my next project. I started small, first just reviewing my notes. Then thinking about how I was going to start the book, then I started the first chapter, and before I knew it, I was writing again.

Sometimes it helps to review past accomplishments. See how much you've done. That helps for me as well.

I hope you're feeling better!