I'm not a hand quilter either (not enough patience), but I would suspect that all the turned under fabric in a hexie quilt could be hard to quilt. Do you think that could be the problem? Also, you might have to adjust the tightness of the quilt in the hoop. Or you might find that you prefer quilting without a hoop. I've tried both ways, and I prefer not to use a hoop. But I've done very little hand quilting!
(Crewels do have sharp points, and big eyes. They're often used for embroidery. I don't know if they're normally used for quilting.)