Wow........that does look hard, especially with the pieces (I think) being all the same shape and no edges. I've never done one with no edge pieces. Funny, there are extra pieces. I wonder if someone else is missing those exact pieces?
Maybe they are spares, in case you lose any. haha What company was it made by? I definitely prefer puzzle pieces to have random shapes. Sure can make it easier. Good job, happystuff!