Picture does help so much! I think anyway...
So it looks to me like you need an extra square(s) in your center gap. I would use a full sized square even if that is a little big. You can fit in the extra, or take up just a little more in a seam or two -- maybe just fixing a wavy seam would do it.
It looks like adding in the center won't affect your light/dark combos and will actually make them work a bit better. It isn't so noticeable in scrappy but when we are doing two-color checkerboard borders, we like to have the light/dark march around the edges. Depending on your measurements, that might mean that the borders themselves are very slightly different. That is, one side may start with dark square with a light in order to get that marching and no dark/dark or light/light combos.
My other thought is that you can put in a piece of background and use it for your label. A little unusual placement but an outside-the-box solution. Honestly though, I don't usually label my projects and never do my donation projects.
Edit/PS: Look at you getting pictures to load! Grats on that
