if your blocks are 17.5 inches square for the heart blocks (finished size), I think those measurements are correct? I can't tell if you have already stitched the rows, but I think not? remember the seam allowance will take up some of the fabric. Once you have the rest of the quilt stitch together, I think it will be easier to add the corners and check if they are the right size. I would remeasure the corner squares to make sure you did have the right size square.