Vintage 60s 70s Ursula of Switzerland Boho Maxi Dress Size Medium?

Hi, This is a great vintage dress marked "Ursula of Switzerland." There is no size, but it seems like a woman's medium based on measurements. It looks small, but the waist expands to 20.5 inches. Measures 20 inches armpit to armpit. In great condition, no tears or holes. Will need a slip dress underneath. Comes from a smoke free home. Thanks for checking out my listing! Please note: in an effort to be more environmentally friendly, your items may arrive in reused boxes. All items will arrive securely packaged. Thank you for allowing me to reduce and reuse!