A word that means someone isn't a people's person, someone who feels much more comfortable without the need of friends or family and keeps to themselves.
Example: I have a talent in music and drawing. There's tons of instrumentals I want to put words to. I'm also trying to hone my skills to draw free-handed which will take a significant amount of time. And as if the dozens of anime series I haven't finished watching wasn't bad enough; in addition there are a great number of other TV shows that I want to catch up on. I don't have the time for nor the inclination to lead a busy social life.
In short, "I'm sort of a ________. You could say, I've got too much on my plate".