This probably better belongs in the "Home Disasters" forum, but thought I'd try here first.

Demo just completed in our tiny master bathroom, 1950's era. My contractor jackhammered up the old floor tile and it is now in the state pictured. You can see two of the joists (running top to bottom in the photo; they are inverted V-shaped) and then there is a lot of the old concrete remaining, which is nowhere near level.

Really really wish we had just removed the top 1980's layer of tile, and then tiled over the original 1950's tile (which was in great shape).

Anyway, wondering how to salvage this mess -- my initial thought was that we should try to remove additional concrete to expose the joists, try to level somehow, and then lay plywood over top.

However, I'm concerned that the original concrete is providing some structural support here, and any additional demo looks dicey.

So, current plan is to pour additional concrete over the old, then lay cement board, then Ditra, and then tile. From my initial research, it looks like one can add bonding agents to the concrete to help it to get along with the old concrete. Also plan to pour at least 3 inches of the new layer to try to reduce cracking.

Any hope this will result in a suitable substrate for tile? Would appreciate any thoughts.