I have a fear there may be weeping and wailing and gnashing my teeth

So as I’ve noted before, working on the Applied Science short stories, has forced me to reassess the plot of Brain From Outer Space. Most particularly, I want to come up with a character arc for Dani other than being a supporting character to Gwen and Steve.
The past couple of weeks I’ve been working on the arc (involving an independent encounter with the bad guy’s agents) and the first couple of scenes look pretty good.
Trouble is, it’s easy to start with a couple of promising scenes. Making them go somewhere interesting and usable (e.g., if the logical thing for the conspiracy to do is kill her immediately, that’s not usable, seeing as they’d probably succeed) is difficult. And I’ve no idea where this is going yet. I don’t outline well; I have to find my plot by writing.
That’s fine when I’m working on the early drafts,, but dang it, I was supposed to be close to a finished version (not a final draft, but at least I’d have all the plot points in place). I’ve been working on this for years (I’m not a fast writer and I only have so much time) and I was confident I’d finally worked out a coherent, usable plot. I soooo did not want to start major reworkings and adding new plot threads.
Too bad. Because I know this new plot will be better—Someday. Whenever it’s finished—and I can’t settle for worse. So if it means another year added before I finish it, so be it. My own fault for fleshing out the background and making Dani more interesting (not to mention Meara, Harry Sato and a few others). When it’s finally done, I’ll be delighted at how much better it is.
But I wish it was going to be done sooner.