Good theory...
But, there is only 1 minutes time span between the face and crouched down (covering the family jewels).
Here's what I thing took place:
Jodi was pointing the gun at Travis.
He knocked the gun out of her hand, he slipped trying to "lunge" at here from being wet.
Then she grabbed the knife (I presume she had it on her body already), then stabbed him in the heart, hence the spatter on the sick.
As Travis is leaning over the sick, she stabs him in the back, head, shoulders.
Travis tries to get away, makes it to hallway and bedroom entrance. He is on all 4's; Jodi grabs him from the back of the head and slits his throat.
After this, she gets the bathmat places his body on top of it and drags his body back to the bathroom. She places his body in the shower, then shoots him in the head from the right side. The bullet went downwards so she was standing over top him.
Then the clean-up begins...