I think your work so far is drop-dead gorgeous, and you're right on track with your border ideas. Because the border will be the drop and not seen on the same plane as the design, you could add stars or not, or repeat the lotus blossom effect of your current outside border after adding strips of the colors you have stacked with the top, or just use strips. Definitely use the fairies on the corners, with the same sashing on the sides to fill out the space as in the squares you've already done with them. Any way you choose to do this will be beautiful, just more active or more sedate on the sides of the bed.