Elizabeth, I'm no help. I take one size in BR/ Gap jeans....and also have some premiums in that size. One of those premium jeans is super tight -- but it is SUPPOSED to be super tight, as it is a legging jean. The other one (different maker) is supposedly a skinny, but is actually almost baggy on me.
I also have actual premium jeans in the size below this -- TR Camerons. And they are super baggy on me. Although they don't fall off done up without a belt, they do fall off the second I unbutton them.
AND I have premium jeans in the size above this -- my Citizens of Humanity -- and they fit snug in the waist and thigh but not too snug.
So. I'm going to order in the size above my BR jeans, and maybe also in the size of my BR jeans. I think. Although I suspect the size up will give me the fit I am after. Because I also have slouchy skinnies from BR from several years back, and those ones are also a size up from my regular, and I love them.