Trouble and plans

On Monday I started work again after 5 weeks of summer vacations.

Near my office is my local pusher quilt shop and i popped in during my lunch break to buy backing for Isabel's quilt.

They have batting there as well and I bought two packs of Heirloom cotton batting.

Now that I added the white sashing to the outer edges of the quilt top the batting is too small. I'm not really sure what to do.
I could rip out the edging on the sides or I could make it narrower because it's only about 1" that's the problem.