Black Relaxed Knee-length Dress with Shoulder+Arm Cut-outs

Black relaxed knee length dress; gathered at waist, boat neckline, and half-length sleeves that have cut-outs. The dress has no label but was made by fashion designer Kim Cathers (label is Kdon), who was on Project Runway Canada (https://kimcathers.com/contact-discollection/). My sister walked for Kim Cathers once and was gifted this dress, which she passed on to me. Here is a link of a picture where Kim Cathers is wearing the same dress (but with a pattern): https://images.app.goo.gl/xztoUTUEwML7rDog7. I lost the original fabric belt but have replaced it with a thin black leather tie; can use any belt or go without. I have worn the dress a few times (5-7) and it's very comfortable but unfortunately doesn't fit anymore. I would say It's good for Size 4-6 (M). It's likely polyester. I've machine washed it in cold water without issues.