I agree with Serenity Stamper's suggestion on something to ground the image. I'm not quite sure about simply reversing the layers, though - because then the blue jeans and t-shirt would be on blue, just like the face and cap are now on orange. Your idea of having the image on a circle would work - even a very pale blue rather than white.
Something that can add a lot of visual interest is piercing - you could add a little to the corners maybe, or in each scallop? But more likely the corners - that would help to frame your sweet image.