Only someone like the person who diagnosed you with the GAD can do a diagnosis, so if you feel there is more than that, then either see them again to discuss it or get a second opinion.
You won't be able to self-diagnose schizophrenia or psychosis and thinking you have one of them might lead you down the wrong path if you try to deal with whatever bothers you. So it is best to leave diagnosis to a professional who could work with you on anything that they think needs your attention.