For those of you currently using the medium sized zoe, how is its slouchiness. When I tried it at the store, even with my stuff in it, it still seemed to kinda stand up on its own more unlike the medium carly I have. I love the slouch of the large but when I tried it in the store over the weekend it seems a tad large for my personal use. So does the bag "break-in" well? does the slouchiness get better over time or should I just go with the larger on who seems to already have the slouch I want?