Excellent post and I tend to agree with you but I also have some questions for you:
*We do not know where the sofa really was that night. When the media call it a "sofa", I would call it a one-seater armchair. IMO a sofa seats 2 or 3 people like the one they were sitting on when the photos were taken of them with the monkey the week before by OP's neighbour and best friend, the Builder with the ladder. I think we have made certain suppositions based on that blood spray by trying to work out how it got there.
*The assumption has been that she must have been down there at the beginning when the domestic violence began to account for this blood spatter. How do you account for it with your scenario?
*The blood spatter on the walls of the stairs had to be accounted for and it appeared to me that his carrying her body down the stairs did not account for it very well.
*We have assumed that she was not injured seriously enough downstairs and was able to go up the stairs perhaps to get her phone.
*The violence downstairs could have begun with the cricket bat rather then the gun which was probably still upstairs.
*Just because he usually keeps his gun or cricket bat upstairs does not mean he could not have secretly gone up to get it when he was angry with her. He could have gone up to get the bat to threaten her at first then brought it downstairs again and held it up to her as if to hit her, saying that if she did not keep quiet about whatever it was, or do whatever he wanted her to do, he would hit her with it. But she refused and he hit her. So she then ran upstairs to phone the police.
*There had been arguing going on earlier in the night before midnight then reported and someone came to check at about 1pm I think. I imagine no violence had occurred at this stage if they had checked Reeva's welfare then.
*But could neighbours really hear this arguing if it was done downstairs? Maybe only if the front door was open.
*Was Reeva trying to escape so she had opened the front door ready to go. But she was so emotional that she had forgotten that her things were upstairs so she had to go up and get them first.
*Was her car door really left and found open or not? Maybe she got to the car and only remembered her things then.
*Can a woman then climb up the stairs after she has been bashed with a cricket bat?
*Would being bashed with a cricket bat cause the blood spatter found on the sofa?
*I do not really think she was going to stay the night after this argument at midnight but had earlier assumed she would (hence the call/text to the Myers about 10pm) so she had placed her things in the bedroom much earlier before they argued.
*So she gets upstairs somehow to get her things and/or to phone either wounded or about to be.
*OP could have even carried her up the stairs with his prosthetic legs still on if she was badly wounded or unconscious.
*He then locks the bedroom door to either keep her captive or to prevent security guards from entering the bedroom. Maybe the front door was still left open? Or the guards might have had spare sets of his keys to get in unannounced.
*Why did he state that the bedroom door was locked otherwise? I have often wondered the point of this.
*If he was keeping her captive, she would still be conscious.
*If he did not want anyone entering the bedroom, she could have been unconscious. But that would not be true as they argued again from 2-3am if neighbours reports are true. This screaming and arguing was heard because he had left the bathroom as well as the balcony doors open and was too angry to think of closing them.
*So maybe they were in the bedroom for the first lot of arguing eg between about 11pm and 1am then it moved into the bathroom with more arguing between 2 and 3am. Reeva might have moved in there with her phone to make a call and he followed her in there with his gun in his hand to stop her.
*Were the screams heard only before or after the first or second bullet of the first volley of three gunshots (if there were 3)? Then 17 minutes silence. No screams heard after the second volley of gunshots?
*If so, that would be very telling and fit into your theory that Reeva was already dead in the bathroom before he fired the second volley through the door.
*Injuries were to her right side so she might have been facing the vanity unit with her phone in her hand as he approached the bathroom. I think that was on the right side of the bathroom as we face it. He fired the shots to kill.
*I had forgotten to add the initial cricket bat bashing in the bedroom theory to this new scenario.
*Usually conflict escalates when you love (supposedly) someone so I am amazed that there are no defensive wounds on Reeva's body. But maybe there are and we have not been told yet or her injuries hide them. It often starts with arguing, then gets more and more physical with smashing of things too (hence I sort of believe that she might have smashed at least one of his trophies downstairs first) before you get physical with each other.
*Only hit men can unemotionally murder someone with one gunshot so there is usually quite a lead up to murder.
*The reason for their arguments? Who knows? We can only guess. Jealousy? Did they both have opposite sex friends? Or was OP the only one in his opinion allowed to flirt with or see other women? Or did Reeva find out a secret about OP that night that he did not want her to know in case she revealed it to others because it would affect his world-wide reputation?
*Their conflict could have been ongoing for weeks before but Reeva thought she could resolve it with her communication skills. As he was a celebrity, she did not want to tell others about her problems with OP apparently. Little did she know who she was dealing with - a narcissistic sociopath. IMO he definitely has NPD (narcissistic personal disorder). It all began in his childhood. If you want to know more, read all of this about the narcissist's mother:
*But there is more about his past that could be relevant too. Does OP have a fear of abandonment? Having had a father who divorced your mother at age 6yo and a mother who died at age 15/16yo, that can trigger an intense fear of abandonment.
*So what we have here is a man who, because of his narcissism, not only feels entitled to any blonde woman of his choosing, he also would feel very threatened if she chose to abandon him (before he abandoned her) due to (what I see as) his probably having this intense fear of abandonment as virtually both parents abandoned him before he became an adult.
*If, on top of that, Reeva could have found out a secret about him during the days of their courtship, which could have threatened his worldwide popularity, sponsorships and reputation (such as taking steroids but he told her he had a plan so he could get away with it). But he pretended they are "herbal". Did she find out that he had the boxes of herbal ones there too in his drawer and the others were in his safe, for example? Of course the first thing he wanted to remove before the police got there, was these steroids. Perhaps it was not really about his financial records. Had Reeva seen him taking steroids (out of his safe) that night? Did she then decide to smash at least one of his trophies (if true) as she then believed he was a fake when she previously respected him so much?
PS I know that Shane will not agree with this theory but IMO it is plausible and just my opinion. Otherwise why would OP choose to murder someone like Reeva who was the epitomy of love, pretend she was an intruder, risk his career in international athletics and a long jail sentence? There has to be more to it - hence the encrypted phones - perhaps.