This doesn't sound weird to me; I find fanfic a lot more intimidating, mostly because you have to keep all the details about the world and the characters straight. That's hard, especially if you're writing fic about a TV show or a long running book series, with a lot of details and characterization. With original stuff you have to do the same but since you wrote the story it's easier to remember them. Your characters are yours and they can evolve naturally, rather than trying to fit what you want to do with the characters into predefined roles, as fanfic demands. So yeah. Don't sweat it. It's not weird or doing it wrong or anything like that.