I know there have been other threads on this but I couldnt find them when i searched 
I currently use a 12l OMM ultra pack and while it does the job and hasn't rubbed in runs upto 6 hours, I don't find it particularly comfy, I feel it is too big, the chest straps too low and the shoulder straps don't fit great!
I'm really petite and was wondering if any other petite ladies have found a small pack that works well for them? I like the idea of the vest style ones but I'm not sure how ajustable they are, store choice seems to be pretty limited so it's hard to try them on 