Every writer I know has trouble writing.
Tidbits about Joseph Heller from Wikipedia:
Shortly after Catch-22 was published, Heller thought of an idea for his next novel, which would become Something Happened, but did not act on it for two years.
All of [Heller’s other] novels sold respectably well, but could not duplicate the success of his debut. Told by an interviewer that he had never produced anything else as good as Catch-22, Heller famously responded, “Who has?”
Heller did not begin work on a story until he had envisioned both a first and last line. The first sentence usually appeared to him “independent of any conscious preparation.” In most cases, the sentence did not inspire a second sentence….
Only when he was almost one-third finished with the novel would he gain a clear vision of what it should be about. At that point… he would rewrite all that he had finished and then continue to the end of the story. The finished version of the novel would often not begin or end with the sentences he had originally envisioned, although he usually tried to include the original opening sentence somewhere in the text.