I realized that it's difficult to make fitting adjustments on my own body by myself. I can't afford a manufactured dummy nor am I confident that something store-bought would be able to replicate my cup size and other dimensions properly, so I conscripted my sister and we made one out of duct tape. My sister and I made this dummy by taping over an old t-shirt and some plastic bags (to cover the legs). It took about 2 hours. I stuffed it with old newspapers and put a hanger inside so I could put it in my closet. If I had to do it again, I would have kept my arms at my sides. I had my arms slightly out, which raised my shoulders, so the dummy isn't so good for getting the look of sleeves right.

Old t-shirt couple plastic bags ~2 rolls of 2 in x 60 ft duct tape newspapers wire hanger