Oh, wow, there's been a lot going on here since I last checked! (I'm finishing a new collection and have been working extra-hard for the last couple of weeks.)
I want to say thanks to everyone who offered encouragement and advice. I finally figured out the mistake that was causing my knots not to hold: I was tying double overhand knots (or double half-hitches? I'm still figuring things out) around the passive thread with the end of the thread I'd been working with, but none with the long tail I'd left when I started. Once I did that, the necklace seemed much more secure, but I did use glue, too, just in case.
Here's how it turned out:
And now I love knotting and have already ordered more Beader's Secret from Pattye!
Happy Weekend, everybody!