I'm not discounting your theory, but I've asked this question several times and no one has been able to answer it...why would she take pictures of Travis in the shower without his knowledge especially since no one was ever going to see those pictures?
I've posed the same question to those who think she's holding a knife or gun on him while taking the shower pics. Why?
My own theory is that she planned to kill him in the bathroom (specifically the shower) to cut down on the amount of evidence. The shower pics are the ruse for her being in the bathroom with him. She meant for him to die in the shower, which is why she dragged him back in there and rinsed off his body. However, it didn't go how she planned it (obviously).
I think the "dropped camera" pic could actually be her setting the camera down while she gets the knife (or gun, I haven't decided which came first, but I'm leaning towards the knife). I think she meant for him to be seated while she killed him, but he got up before the first stab wound or she stabbed him in the head as he was getting up.