You would so rock this style Rita! I would covet it myself if I didn't already have a black Kate Spade version with white polka dots! I bet it would fit you well especially since you're petite. How would it look with the black obi belt instead of the ribbon? That might counter the cutesiness of the polka dots.
I unapologetically shop in junior's every so often. I got my cute rust orange and navy peacoats in the junior's section at Nordstrom!