That screenshot of the story view looks daunting. It's hard to approach a single blank page. When you see them all... It's like, What did I get myself into into? On the other hand it gives you that structure to organize and plan around. Like you mentioned with the index cards. I wish I had some really great advice but I struggle with the exact same stuff. Best I can say is enjoy the journey and the destination takes care of itself.
Post more! It's something I've thought about. Where is the balance between disposable social media stuff and longer form stuff? I say post more, gain experience.
As daunting as seeing the whole project is, I actually like having that visualization of progress. No matter how much more there is to do, if I can see progress happening, I’m happy!