If as you say the two double bottom parts we are seeing are upside down, perhaps you can explain the two close together parallel lines running from top to bottom on the center line of one of the sections as well as other anomalies indicated as follows:
looks nothing like any ship's bottom I have ever seen.
In the centre is the keel bar (look at pic 2) on the sides the bilge keel (look at pic 1). Your bottom "anomalies" are pars where the hull plating is missing. Pic 3 show what is between. If that does not look for you like a ship bottom, your problem.
The single end boilers are in a cluster on the sea bed to the right of the stern section. In your last post, you say the No. LP cylinder is north east of the stern section. You do not say how far to the north east. That being the case it incorporated part of the heavy, engine bed plate so that's where it fell to the bottom from the ship. it most certainly did not swirl around but would have dropped like a stone to the bottom. Since the DB parts are also to the north east, I think you can safely say that spot is very near to where the ship sank and nowhere near where the bow finally ended up.
The boilers are about the spot where the ship broke at the surface.