Try new things and keep track of how well they work. Don't worry about whether your process looks like any other writer's process.
Dear Story Nurse, I'm not the kind of writer who can start editing a draft as soon as I'm done with it. By the time I stumble over the finish line of a novel-length project, I need some time to emotionally detach from the story before I can think about how I want to change … Continue reading #120: Separation Before Revision, Part Two
Without a degree of separation between book and self, revision is far more difficult, and may be impossible.
What I don't recommend is beginning at the beginning. Since you need an ending to work toward, begin with that ending.
Depression is a pack of lies layered over the core truth that you are a writer.
Start with the story that's most often or most strongly on your mind, and stick with it until it's done.
Endings do need to bring at least the major story threads to a resting point, but they're primarily emotional experiences.
It sounds like you have some thoughts or feelings about completing your draft that still need your attention and aren't ready for you to move on yet.
Until you make your abstract goal more solid and figure out what makes it personally meaningful to you, it will keep losing out to shiny new ideas.
Every single approach to writing is perfectly okay, as long as it's in line with the kind of writer you want to be.