Lip droop - what can I do to achieve symmetry? (Photo)

For as long as I can remember, my right top lip droops. You can see when my lips are pressed together how the line that forms drops dramatically on the right. Also, one corner of my mouth is considerably higher. It's also highlighted by a lack of fullness on my upper lip (right side). I was so concerned about it that my doctor finally ordered an MRI where everything checked out normal. I've heard Botox can help, and someone else suggested a lip implant?! What can I do to achieve symmetry?