I finally managed to get this done. :) I ended up having to redo a lot of the little HSTs because I kept making really silly, totally avoidable mistakes on them, but in the end I managed to get everything put together fine.
I was worried about it not being the right size when it was all done as I've not done a proper pieced block before, but it came out at 12.5", which I'm pleased about :). Some of my intersections aren't exactly matched, but hopefully they're close enough that nobody will notice unless they look really closely!
Now, onto February!