Further to this, I ended up moving my saddle back almost 1 cm and swapping out the 120 mm stem for a 100 mm stem while maintaining a slightly raised (i.e. non-horizontal) shifter position on the bar. So, essentially like in
post 24, save for a shorter stem.
I think I've got my saddle in a better position now. I think I had it too far forward. With 1 cm back on the saddle and 2 cm back on the bar I've decreased my reach by 1 cm, and it has made quite a difference in how the bikes feels. It handles a lot better with the shorter stem, plus I'm not as stretched out, so I feel more confident.
So that's the fit for now.