Beautiful quilt! I think the yellow sets it off, as the complementary color to purple, but either narrower (piping, faux piping, flange, peeper) or just a shade lighter. It comes across on my monitor as so bright it overwhelms the whole, but the same hue in a tad lighter shade would be more mellow while still giving a hit of zing. Shifting to the light lavender instead of the white would also be a good option.