It's Middle of the Book Syndrome: I'm half-way through and I'm bogged down. There's a mad poisoner, a screaming baby, a funeral, squabbling relatives and a pouting 15 y.o. girl. What more does anyone need? But they're American VIctorians so their behaviors are constrained (except for the baby). I'm just sorting out who does what to whom and when. And I have nine more months to get through as well as a Confederate raid on Washington.
In reality, I'm quite afraid I will have wound up the tale well before 50,000 words. UO was annoyed because he hit 50,000 and still hadn't gotten to "The End;" I think I can get there a lot more quickly but then I will have failed at the whole abstract "novels = 50,000 words" rubric. Dammit.
Anyway, that's my biggest fear at the moment, because if it isn't 50K words, it won't get published. (Never mind that it needs to be good, however that's defined.)