Thank you all for your responses -- especially jokir44. I have spent many hours studying properties of cotton but know almost nothing about silk. This quilt is for my 4yo niece, but I make 100% cotton baby quilts and understand how to make them durable and washable. I usually expect them to be washed in cold water/dried on low heat once a week. With quilting at 2" apart, that should hold up for 20+ years without issue; denser quilting lasts up to 50 years. But my concern with this quilt is that everywhere except over the applique, I never have quilting more than 1.125" apart and typically it's much closer than that so that will mean a lot of stress would be put on the applique fabric & stitching.
I am really just wanting to be done with this quilt. It's the first time I didn't follow a pattern & it's been super challenging. It's a combination of 5 different quilts that I pulled from/modified for different parts of it & has been a great learning experience but I'm growing more eager to just be done with it by the minute and was more than willing to buy 2 spools of silk thread so I didn't have to change colors 13x, but it sounds like that's what I'm going to be doing. Argh! So much for finishing the dreadful thing this month. I do think I'm going to at least spend the $30 for a pack of Bernina bobbins. Only having 5 & needing to keep unwinding & rewinding with a new color is getting old fast.