That sounds right to me, except that he does not splash water on his face. The water at the edge of the sink was from the water dripping from his face and hands as he propped himself over the sink. If he ran the water, the blood in the sink would not have dried that way ... it had landed into a dry sink.
Also, since the camera was built for only right-handed operation, and JA is a leftie by nature, she would wield the gun in her left hand, hoping for a nice clean death in the shower with one shot.
She may have had the gun tucked in her waistband behind her back, as they do in the movies (as they were both movie buffs).
She had not contemplated the gun jamming, as she told Flores that if she had it in her to kill Travis, she would shoot him and keep shooting until he was dead. If you are only imagining a hypothetical situation, who would say that they would keep on shooting until they were dead? I would just say that I would shoot them. Period.
I also think that the camera and the shell casing got kicked around during the bloody scuffle down the hallway where Travis finally "stopped", as JA truthfully testified that "he wouldn't stop", although her version was meant to suggest that he would not stop attacking her, when in fact he wouldn't stop moving away from her, and he wouldn't stop breathing/living.
