Hey Stacy...
I think you are doing fabulous if you can hold on to that 31 pound bar all the way through PH leg segments!!! You should be very proud! I have very strong legs but always seem to have to drop the weight during those nasty low ends.
I think doing the entire CTX series would do wonders for you. You already are pretty slim and just need the extra "edge". I am telling you, CTX gave me that. I got much leaner in a very short amount of time, plus as a fringe benefit, IMAX got much easier as well. Especially since you do no cardio now, this type of cardio mixed with weight training might be exactly what you need. With CTX, the only thing I would worry about is not enough heavy upper body, but you can add that in on another day if you want. Or skip the body part segments all together and mix up your own with PS. You could do each body part of PS coupled with the cardio in CTX.
Both of these series are awesome and I think you would not regret getting both. You seem pretty strong so I think PS will have limited value for you, and CTX has so much stuff..upper body, lower body, all abs, tons of different cardio, intervals...it truly is the "complete" package...
Good Luck in whatever you choose and a big CONGRATULATIONS on such wonderful progress!!
Janice