Hi Merlot. When I weaned (many years ago now) my foal from my mare, I ended up taking the mare to another place for a month mainly because of my facilities (well technically lack of) at the time. When she returned, the two greeted each other but neither showed any interest in resuming the nursing part of the relationship. I know of some folks who did it pretty much the way you have being doing - increasing the length of separation to the point a complete separation is made (adjoining pastures) that prevents nursing. It was a success and neither mare nor foal were stressed out any point. That way took longer than the traditional quick method but these folks had the time and facilities to make it happen.
As a side note, I've been to production sales where a lot of the foals offered gave every evidence of being recently weaned just a few days (if that, I think) before the sale. It's a sad sight watching them looking to nurse off each other.
On a brighter note, I hope there will be many installments made by Zephyr as he writes home while he is away at summer camp.