If this is your first piecing project, I think I would just cut some squares and practice piecing. Maybe make some 9 patches and put them together, just to get the feel of the piecing. If you think you cut the fabric wrong, it's okay. We've all travelled that road and it's not the end of the world! Just get some similar fabric and try, try again. I really would try making a smaller and less complicated project first. Maybe some placemats or a table runner to begin with. You'll be off and running after that!