I'm a plus size girl too, so I totally feel your pain on that! Plus, those little bags like the shoulder, make my arms look huge, which I so don't need. *L*
I have a Carly too, and love her.
I've had GREAT luck with my large ergo tote. It fits like a dream and is so light. I love it.
Ali also fits really well, and I have no problems with her.
I bought a large ergo hobo but have found that when I try and keep it between my arm and my side (if that makes sense) the strap falls off my shoulder. In order for it to stay on, I need to push the bag back behind my armpit to carry it, so my arm will be at my side, and the bag part will be out behind my arm. (I didn't explain that very well, so I hope it makes sense anyway. *L*)
When I tried on a gallery tote it looked pretty good on me and seemed comfortable, but I dunno about those skinny straps.
**edit**
Oh also, I bought a Soho hobo when I was working at the outlet. It's the one that's straight across the top so it slouches a little bit and it fit really well too. (it's not the crescent shaped Soho hobo, I'm talking about the other one.)