(Lack of) Creativity

It may just be the weather (nonstop rain), but I feel my creativity is absent, even as I need it the most. Trying to set up more items in my CafePress store, I must be original, creative, thorough, detailed, exact. And as I am struggling, my hope fades that I can support myself at all.
I know that I must diligently plod onward, but I don't feel as if I can accomplish anything worthwhile. It seems a daunting task to compete with so many brilliant designers. Everything I do seems unfinished, incomplete and completely unprofessional.
I would like to keep my t-shirt designs along the line of nature; my only 'completed' design so far is a tree. Until I am otherwise inspired, I will continue to attempt some additional tree designs and then move on, maybe to flowers and birds. Why is this so hard?
Being in my own world as I am, it really is up to me to pull myself together, to sit myself down and think, to come up with some good ideas and to work them out on paper. This is my undertaking, my personal venture. It takes hard work to get things done right. And, I fear, I have a lot of hard work to go.