I think you’re asking why the setting triangles are larger than the side of your blocks. It’s because when you set a square on point, the diameter of the square (now the width of the block) is longer than the side of your square was. I believe it’s the length of the side x 1.4.
Looking at your blocks, it seems like they won’t connect in the intended way if set on point, but if you like the new look, go for it. I would not, myself, chop any up to make setting triangles, as I think it would destroy your design.
Better, I think, to find a new fabric to serve as a frame. I’ve used Kona to good effect that way. It frames the design and can, if you like, sort of drop back and lift the design area forward or bring out certain colors in your blocks,
hugs,
charlotte