Fun and satisfying! I finished all the levels!
I was confused by some mechanics (esp not knowing about rotating items, and which could be moved) but the page description cleared that all up. The main frustrating thing I had was when I failed a level, it all reset - I wish it remembered the solution I had tried, so I could start from there and make minor tweaks, rather than having to start from scratch! But it made me try hard to count and plan perfectly rather than just winging it :P
I love puzzles, and I like the mechanics and levels you came up with! Great job