Why do I always feel empty? What's wrong with me?

What I'm getting from the information you provided, is that nothing happened and you just feel empty for no reason. You don't need help from a psychiatrist or anything, what I would recommend is to start new hobbies such as hiking, yoga, painting.. go to an art supply store and you can find a lot of interesting art activities to do with your spare time. Find a zen book and read it every day, some people find peace and fulfillment through that. Some people start reading the bible or form a strong faith in some religion and that helps them. You just have to explore the world and what these days have to offer, discover what makes you happy and stick with it. I know that feeling and I myself found happiness in reading inspirational books and spending more time with my family. It takes some time but there's not much one can do.. the best element is positivity