First off--your piece is absolutely stunning and if this is an example of your capabilities, I will be waiting with bated breath for your next piece! Stunning!
Now a question about how you put the picture together. Did you sew a crazy quilt-type block and then cut out the dress or are all those little pieces appliqued by hand or machine, or are they just fused to the background? If they are just fused, you should probably secure them by stitching along all those edges. If you sewed them together and then cut out the dress, it should at least be secured around its edges. Same with the hair, which seems to be bias tape?? You could just sew very close to the edges to secure it. Or you could put a fine tulle over the whole piece and then quilt it thru all layers.