One of the things that you are guaranteed to be an expert on is your own personal experience. The movie world is full of great movies that are extremely personal to the people who wrote them. From Lady Bird and The Big Sick, where the story is either inspired by or influenced by the filmmaker’s personal experience, to The Pursuit of Happyness, Hidden Figures, and The Wolf of Wall Street, where the story is based on a book, written by the person who’s gone through these experiences.
The reason why these stories are so good is that the characters in these stories are generally the authors themselves. In many other cases, the story, subplots, and characters could be inspired by real life but also remain hidden under a cloud of fiction. A good example of these types of storytellers are the likes of J.K. Rowling, whose deep depression inspired the creation of the “dementors” in Harry Potter; Jerry Siegel, who created Superman as a result of being bullied in school; William Moulton Marston, who created Wonder Woman based on his own personal experience with powerful women; and as recently as Larry David and Jerry Seinfeld, creating a TV show where its characters and plots are based on the writers’ actual life experiences.
There are many, many more writers who created popular characters and stories based on their own life experiences and hid them well within the confines of fiction and genre so that they are not considered “based on true events.” Try thinking of some life events, traumas, or catharses that you could write about, either literally or as allegories; every human being should have at least one of these in their arsenal.