I was taught not to prewash anything, unless you think it will really bleed. And since I have four cats, everything gets washed and dried in the machines. I wash in cold water and have never had problems with bleeding. Plus, I prefer the "old fashioned" look to quilted products, with some wrinkling.
Make sure when you iron that you are "Pressing" and not "Scrubbing". Put your iron down on the fabric, press firmly for a few seconds without moving and lift. When you move your iron back and forth as you go, you can stretch the fabric. You can give it a burst of steam if needed.
I think your wrinkles will quilt out, but it's the wrinkles that give a quilt that homey, well-loved old fashioned look. (In my never to be humble opinion. LOL)
Your quilt top is beautiful, by the way!!! Great Job. But if you are that unhappy with it, better just discard it. TO ME!!!!!!