I think this is just another detail OP is deliberately lying about, which is why I wish they could track down the call and establish exactly what he said when he described Reeva's injuries.
Yes, and I also think it's possible that OP was so scared/alarmed about what he'd done, due to the consequences for himself, that he instinctively wanted RS' body away from him and away from his house. He moved her despite, I believe, knowing a seriously injured person shouldn't be moved, and carried her downstairs. An attempt to disassociate himself from what he'd done in addition to compromising the crime scene. He tried unsuccessfully to get Stander to take her.
When giving his evidence OP also criticised Stipp's help, trying to reinforce he was seeking help, and Stipp didn't know what he was doing. Along with claims that he didn't shoot RS, or anyone, he only shot at the door.
It all indicates to me that OP is in denial, in addition to trying to save his own skin. He continues to disassociate himself from the crime. JMO
I believe his distress, anxiety, is more about the consequences he is going to have to face than the fact that RS lost her life as shown by his evidence in court.