My butt actually got bigger when I was on my FIRM kick awhile back, not doing the PINK FIRMS but using the Fanny Lifter and TransFIRMer did TERRIBLE things to my lower body, butt got bigger and my quads got bulky plus those tall step ups killed my knees. I could not figure out WHY I was gaining inches because everyone I knew, or heard had used the FIRM, got smaller using this system. NOT ME
Even though I havn't been with it too long, I totally agree with the others, Barre workouts are amazing for leaning out your lower body. I see a difference already and I had pretty much given up on ever seeing a slimmer lower body again. I know, FOR ME, weighted lower body work and Step just doesn't work for me, well, it works, just doesn't give me the results I am personally after.
So,DEFINITELY try a Barre workout
there are quite a few really good ones out there right now and hopefully MANY more coming in the future.
Good Luck