I can think of one very macabre scenario in which the enraged OP having shot twice through the door (bullet holes A & B) one of which hits Reeva in the hip. She falls backwards onto the magazine rack. OP then removes the right-most panel enters the toilette with the panel in hand, positions or props the bottom panel inline with the right side of her head/arm (which is now resting near or on the toilette), and fires 2 shots through it ... that would explain:
- the small diameter of the grouping of the splinters observed around the arm wound, and her forearm
- the slight curvature of the bullet pathway through the door at bullet hole D as observed by W - this would be due to mobile status vs fixed status of the panel
- the distribution of the brain matter on the toilette lid - whereas imo, it is somewhat difficult to reconcile the brain tissue pattern of distribution from bullet pathway of holes C or D through this panel fixed to the door
- the large splinter found in the toilet bowl/basin
- the large bullet fragment found in the toilet/basin
- the possible 5th cartridge found in the toilet/basin (my speculation)
I know it seems far fetched, but so does the unexplained pellet hole in the bedroom door, the unexplained damage to the bedroom door and locks, the unexplained damage to the bathroom tiles and the bath's metal plumbing cover.