Sometimes the changes I think of making to my story aren't better or worse than what I already have. It's just preference. And I have to wonder, do I really prefer one over the other?
I think on a subconscious level, I wanted to explore every possibility, every unturned stone, and then pick what was best out of all of them. But with so many characters, complexities, mysteries, relationships, themes, and opportunities for worldbuilding, it's unrealistic to do that. And once the story reaches a certain point, it's not a better or worse option anymore, it's just a different option. Often it becomes an exchange. If I switch this, I can gain this and that, but lose this and that. Sometimes it's not.
There's a saying for movie-makers: "A movie is never finished, only abandoned," meaning, one can always do more work on it. He just finds a good spot to stop.
I think I'm reaching that point with some of the core elements of my story--like a lot of my characters and plot. I don't need to keep adding and changing them. They aren't good enough, they're great enough.
And when I notice awesome opportunities for an intriguing relationship or plot option--I can't always take them. There are too many. And frankly, my manuscript is already way too long. There has to be a point where I say, "This is great enough," because there is always more.
It's strange to think that two years ago, when I was working on my first draft, I had moments where I suffered from writer's block and stared at the blank page, overwhelmed and in a writer's depression. I've gone from wondering what in the world I should write next to having so many story avenues that I can't even explore them all.
I think that's a good sign.
I feel like it's a sign that I'm going the right direction, and that my story has become rich and complex. At least I hope. I can't please everyone, but hopefully whether or not people like my novel will come down to preference rather than weak writing.
So rather than explore every single unturned stone, I need to fix my story's actual, blatant problems, until even those reach the preference point. Then, after my beta-readers, I'll go through and fix the next set of problems, and again with an agent, and again with a publisher (I hope).
For today, just know that if you are working on a novel, you might reach a point where you see too many possibilities. That's good. But you'll have to be okay with the fact you can't explore them all.