Scoliosis, Flat Lower Back On the Other Side

I’ve been seeing my physical therapist, and the exercises/stretches she’s given me have been working. I’ve somehow straightened out my front torso, and also my back has been straightened out by a few degrees. At this point, I don’t even care about my curvature, my only concern right now is this “lower back flatness” (for lack of a better word) on one side, which is my left side. My right side seems pretty normal.

So, I was just wondering if you guys have any stretches/exercises to remedy this.
Here are some pics:
http://postimg.org/image/3uu36nrch/

(Right Side View)
http://postimg.org/image/b62f3rdo5/

(Left Side View)

Thanks in advance!