my first free writing piece

These days I prepared for my GRE analytical writing test. Frankly, this is really painful, especially for me. I think I might be got Writer's Block, though I don't think that I am a real writer.

What is Writer's Block? Let's take a look at the explanation in Wikipedia, "Writer's block is a phenomenon involving temporary loss of ablitiy to begin or continue writing, usually due to lack of inspiration or creativity."  To this explanation, I would like to use one of my GRE sentences to express my feeling— I fundamentally agree with the speaker that WB is a phenomennon involving temporary loss of ability to begin or continue writing. However, my problem is nothing related to lack of inspiration or creativity.  I think the problem is I care so much about what I am trying to write. I admit that I have a perfectionist tendency. I put so much time before I start to write. When I begin, I often write carefully and critically. I focus on every word that I choose, afraid to make any mistake. As a result, it costs me several hours to write just a four-hundred-word essay. what is worse, I do not satisfied with what I wrote often. This made me very depressed for a while. I want to get out of this corner, then I tried free writing. This is the first piece.

Hope any of you give me some constructive advice or share your writing experience with me. That is very helpful and highly appreciated.