I'm on the verge of ordering a Chloe Betty bag and was wondering if there's a big difference between the strap length of the medium bag vs. the large bag. I prefer the medium sized Betty, but am concerned that it may not be easy to wear over the shoulders (I definitely don't want it riding up my arm!) Could any Chloe Betty owners out there let me know what the drop length is like for the medium sized Betty? Is it comfortable to wear over the shoulder?