The lighting on image one is not bad . . . but #5 is excellent. It is actually "Rembrandt" lighting. #2 is too evenly lit from left and right. The left rear light should be backed off some, to create about a 2 to 1 ratio as in image #5.
Your black and white conversions don't work for me, but that is another whole subject in itself. They seem to have lost the nice tonal transitions seen in image #5.
Suggestions to improve . . .
1) The subject's body is too "front-on" facing the camera. Having her at about a 45 degree angle from the camera would make her look more shapely and attractive.
2) In the first two images there is too much of the white of her eyes showing. Best to have the subject looking straight ahead which can be done by having her look away from camera, or turning her head more toward the camera as in image #5.
3) When I was taught studio lighting, my mentor would not let me use more than my main light until I had it's position and direction mastered. Then and only then was I permitted to add the second light . . .and then even later, a hair or background light. It's amazing how much more you will learn to understand the effects of your main light when it used by itself.

In the diagrams above, I totally disagree with the main light being aimed behind the subject to try and help light the background. The main light should be in close . . and aimed across in front of the subject using the feathered light from the edge of the light source. To summarize I would suggest reading up on some really good posing ideas . . . and shoot for the next week with only one light.
Umbrellas have their place . . but not so much in learning lighting as the spillage of light from the rear of the umbrella is very difficult to see and to control.

Hope that helps . . .