His post-shooting account of his actions undermines his account of pre-shooting state of mind, reasoning. Immediately after shooting through door, he abandons his ground to get his legs. He swaps out combat posture for more height, stability in terms of "footing," whereas pre-shooting he rushes to confront perceived danger without this advantage. Post-shooting, by his own account of it, he acts as if he knows what he could not yet know--that there is no threat and Reeva is not in bed.
Moving back down the corridor, he is not watching his back, aware of possible hiding places, entry points. It seems the fear-propelled adrenaline no longer surges. He does not call out to Reeva, is not concerned about her safety any longer, or his own, only getting his legs on, for which he must turn on the light, thus noticing Reeva is not in bed and putting two and two together.
Posters here say that in SA typically more than one invader enters. How does OP know he has vanquished first intruder? That first could still be alive and pursue him down corridor. A second could climb up bathroom window. And Reeva, whom he tried to protect no longer needs protection? No longer a need to call out, ask for her help or in any way relate to her as he moves down the hall, or when he gets into the bedroom, even before turning on the light?
In post-shooting account, as in pre, there's a person missing: Reeva. No accounting for Reeva's part in the script. More baffling is that all thoughts of, reactions to extreme danger factor so easily dissipate with the discharge of the gun.