This is such a beautiful essay and it captures so many of the same emotions I had as well. I, too, was fortunate to produce more breastmilk than my adorably chubby infants needed and started running out of space in my deep freezer. I was able to donate most of my freezer supply to a milk bank but would have loved to have had a closer connection to the recipient(s). It all felt very clinical (I think I had to submit medical records proving I was healthy and free of any conditions--I can't recall as it was nearly 14 years ago).
Also, seeing that photo of the empty freezer in your essay made me think of my empty deep freezer. It was so sad and forlorn after being emptied and I did feel a brief pang of regret. Every single bag or Medela storage tube represented time spent attached to the pump rather than relaxing or spending time with my baby. But I think reminding myself that my contributions helped a healthy chubby baby certainly helped soothe that hurt.