Hate to say it cuz I'll be cursed......but I never prewash fabric or batting (can't even understand the thought of washing batting) have never had problems in the many years I've been quilting. I do wash after the quilt is completed.
Also only use Quilter Dream and swear by it! I love the antique look and love the crinkles also.
I think your quilt is beautiful as it is and the perfect size for a baby quilt. Could it be a big bigger...yes....but it's fine just as it is....remember the baby isn't all that big and many times get swallowed up in a bigger quilt.