I LOVE LOVE LOVE our puppia harnesses. Adie is an escape artist and it is the only harness she can't get out of. Plus it is cute.
I bought mine from
happydog@happydogplace.com
The are also sellers on Amazon and are terrific sellers. They caught an ordering mistake I made and emailed me to double check it. They ship really fast too.
As far as the size...My shih tzu weighs anywhere from 11 to 13 pounds depending on her appetite. She wears the medium and it fits her well. The neck is just a bit snug going over her head but she doesn't mind. It isn't any different than some of the tees I have put on her LOL.
Good luck and let me say that the turquoise colored ones are really bright and pretty. That is what Skeeter has.