Miscalculation

Here's a little problem child:
LC & I are making this baby quilt for some friends (who, coincidently enough, have a new baby). I figured out how big the inner pieces would need to be in order to use this triangular pieced border. It's kind of noticeable in this shot, but the fabrics are from a line of Beatrix Potter fabric - with large scenes from her books in the center. The blue has faint white-lined images of her characters. The backing we have is like the center panel, but in a toile format.
Only thing is, I apparently figured wrong. See that gap between the completed section & the right-hand border? Hard to miss.
What we need to work out now, is whether it's fixable - like are the seams a little too narrow on the triangle pieces? Do we make a new, slightly wider border (the cream with little specks which are actually radishes)? Or do we trash the triangle border entirely & just finish it off without it?