Personally I love the size of the Jaraden SoHo although I'm not very tall, 5'5" either. Lol I also don't find it to be too thick in the width as it stays collapsed unless you use the outside pockets for storage.
I purchased Yazmin's SoHo from Kristin, (Maximo) and I agree after comparing it to the Sadie on her site the size and style's very much the same!
Yazmin's stands 9" tall and is 11" from her chest to her tail and feels quite comfortable in her bag so If I had to choose, it would be the Sadie.
Good luck, I'm sure Lu will be comfortable in either bag you choose.
Sadie Mia Michele Black Carrier