I want to be a writer of novels, plays, screenplays, in addition to directing. How should I pursue my interest?

Writing for novels, plays and screenplays are all very different. Different format, different pre-conditions, different rules. For example, you must be aware of physical space when writing a play, although that's not completely necessary for a novel or screenplay. You can do all three, but making a career out of all three will be very challenging and may not even be worth it. Choose one and make that your focus point.

Start with this question: If you were given the option, which would you rather do? Read a book, watch a play, or watch a movie? That should at least tell you what you're most passionate about out of all three.