What can be done to prevent my upper lip from being pushed forward as seen in the following photos? (Photo)

I use to have severe overbite until I had braces.My braces have been removed since November of 2011.I continue to wear my retainer; however, in the first 6 months there was a period of a week or two that I did not wear them and at the time felt my retainer/teeth had moved.Over the last six months,I went back to my orthodontist but was told my teeth were fine and nothing was wrong with my upper lip.I can feel the difference and notice my lip pushed forward especially in photos.What can be done?