The east, the rising sun, is the most suitable place in the east, which is very suitable from the five elements. I think you should prioritize. If your painting is very good and can give you the biggest and most suitable decoration in terms of decorative effect and color, then you can consider covering the mirror, spraying some colored paint, simply covering it, or buying some small wall stickers to deal with it.
Size doesn't matter much. Consider giving this cross stitch a larger frame, about 15cm in width. Pay attention to the color.