I support the idea of using a Trello. Hell, use two. One public with vague names of tasks completed, just to show that you are making progress is ok, so long as you have the tasks representing the actual remaining work, and a second that is private just to keep yourself on your plan. Then, **stick to that plan**.
As for the remaining work: I think it's time to cut the "extras" you've promised from Chapter 1 for a "1.0" release. Instead, start leaning more towards the Hello Games approach, and release enough of a "1.0" that you can call it such. From there, prepare "1.0.x" through "1.1" with the extras. (here I'm referring to "Chapter 1" as your effective "1.0", so that you can give yourself "version bandwidth" in the minor releases for the extras you've promised, and just plan chapter 2 as 2.0, 3 as 3.0, etc.) Otherwise, you're just pissing in the wind.