I don't think there's anything wrong with piano midi! Part of music is choosing the right instrumentation (which I am also still trying to learn as much as I can about), but a lot of it is the process of creating and seeing if it feels right. I think that based on the description of your process, it sounds very similar to my process which is more of a composition through discovery method rather than having blueprints ahead of time. Both are perfectly valid forms of composition, but I like the ability to be more flexible and creative in your way!
Thanks for sending the order of your tracks. Now I get to listen to it again and hear an entirely new story progression!