I don't feel competent to critique your work as poetry but because it's been sitting here a while I'll make one comment that might help.
The word "footfall" can imply a number of steps rather than just a single step: "I recognised her footfall on the path outside the house".
So you could just as well use the singular "footfall" in the final line, the heaviness of each step – and to my ear the line finishes on that downbeat a little better without the "s".
Here is a poetic use of footfall that I found online:
"The earth adores her footfall. Its shadows flee before the brilliance of her eyes."
As I said, it's just something that occurred to me when I read your poem.