That is just beautiful! I have never quilted on minky, but I know it is difficult. My sister is just made a baby quilt out of minky and was distressed at how the fabric stretched. I know she changed her original quilting pattern idea for something simple. I wish I could remember what she did.
But there will be others here who will have real suggestions. Is there a way you could sort of practice on scraps? I think my sister said that would have helped her, and she teaches quilt workshops and is very experienced in the art of quilting. Who knows, she may even catch this thread and offer her good advice.
Dina