As I see it, your time belongs to you.
There are things you have to do with it (work, help parents, sleep, etc) but the rest is yours.
It's ok to carve out time for something that helps you grow as a person like illustrating and reading and such.
You don't have to feel guilty for being "unproductive" in other people's eyes.
This is something that took me a long time to learn. My dad was very hard on me and my sisters so taking time for myself to just chill makes me feel very guilty, even though it's necessary for everyone to do that from time to time.