Ok, you've got this far...why don't you take a risk, get some thin batting or fleece, back it with flannel (or leave out batting and back it with fleece) tie the quilt then toss it in the wash and see how it goes.
I think your colours/design are really good and the fabric is gorgeous. This is a little guy's flannel quilt, which is going to be loved to bits and dragged everywhere. Every quilt is a learning process for everyone...so don't be so hard on yourself..be bold...and then start planning your next quilting adventure!