What to do?
There's plenty of advice online, but I found Ken Levine's suggestions useful for me. I went back, added a scene and put a note in the beginning of the story where I need to add information when I return to edit the rough draft.
The most important thing to remember is that what I have IS a rough draft. I will have to layer in more emotion, more sensory detail, and take out redundant phrases along with tired old words the second time around.
Nevertheless, I am happy with what has been happening in the story. It has been fun! I think I'll try the writing challenge next year, too.