Truely a lesson learned. But not all is lost. If you haven't done the binding yet, and maybe others will not agree, I would cut the size of the quilt down and bat, with a thin bat,and put a lighter weight backing on. Forgetting about the fleece backing. Since you are making this for a gift no one will be the wiser that you needed to add a new back, requilt it and bind it again. My though on the fleece is that even with a thin bat it will increase how heavy the quilt is adding more fleece will make it even heavier.