OK - This lighting requires a dark background. Few things worse than a wrinkled white background anyway. If you go white it must be with no detail.

I'll come back to that. I think the lights are perfect for what we would call a low-key image. That is one in which there are relatively dark shadows - BUT it needs a dark background. Looking at the nose shadow, I think your main light is about the right spot. You could do with a small amount of fill close to the camera and just a bit higher than the lens. This needs to be a stop maybe stop and a half less light than the fill as measured AT the subject. Just enough to soften the shadows a bit and put some catchlight in her eyes. A reflector over to camera left and no more than about 30 degrees or so off the camera-to-subject axis could also work well. In any case, a fill light never casts any shadows, that is the job of the main light.

You have what is known as a mixed-key image - subject and lighting is low-key, background is high key. Not a horrible thing, but one should know the rules before breaking them so when you DO break them it is for a reason - not a mistake.

Let's get back to the background: If you go white, that is high key and you need to light the background so that is is just a bit brighter than the subject - 1 to 1 1/2 stops usually works well. NO DETAIL in the white. THEN you generally want to light the subject a bit flatter (more evenly - not so much shadow). Subject then would wear lighter clothing - whites and pastels.

Try this: exact same image with the same lighting but use that black background. Her hair may well blend into the background since she has dark hair, but the flower in the hair should help. Forget the hair light for now. Get good images with ONE light - may one and a reflector - before adding a second light. Trust me- if you cannot get good images with one light, adding more is not the answer.

Always get that umbrella as close to the subjects as you can, that will give the softest light. The shadows I see are a bit hard - not horrible, but getting the umbrella closer will give a more gentle highlight-to-shadow transition.

I do not think you need more light - exposure on her face looks perfect.

It is easier to show sometimes than to describe. Here is an example of each.

In the specific example you posted (your next photo may be different) your "key" light (the one on camera-right) is a little too high in the air. And your "fill" light (the one on camera-left) is either too weak, or too far away (the shadows are too dark).
You're are sure doing better than many beginners...don't be frustrated. Remember also: anything we may tell you is based on the specific example you show us, and will be superseded by your ongoing experience.
You're doing great, dude...keep it going!

In the specific example you posted (your next photo may be different) your "key" light (the one on camera-right) is a little too high in the air. And your "fill" light (the one on camera-left) is either too weak, or too far away (the shadows are too dark).
You're are sure doing better than many beginners...don't be frustrated. Remember also: anything we may tell you is based on the specific example you show us, and will be superseded by your ongoing experience.
You're doing great, dude...keep it going!

It is not easy to tell you exactly what to adjust without seeing your lighting arrangement.
Ultimately this can be as much art as science depending on the look you are seeking.
Some initial observations:
1) Move the back drop further back.
2) Avoid lighting the back drop directly
3) Your example photo seems a little over exposed to me.
4) Try using a larger f/stop (smaller number, (f/4.0) to help blur the background (eliminate folds and fabric texture)
5) Try using a light pointed at the back of your subjects head to provide some rim lighting.
6) Work with your fixed lighting (non strobe) first as it is generally easier to adjust and modify (unless you understand your strobe's manual settings and can dependably trigger it remotely.)
7) Experiment and experiment until you find the look YOU want and like. That is the best way to learn.

Good luck and keep on trying until you develop a style you like and can control.

It is not easy to tell you exactly what to adjust without seeing your lighting arrangement.
Ultimately this can be as much art as science depending on the look you are seeking.
Some initial observations:
1) Move the back drop further back.
2) Avoid lighting the back drop directly
3) Your example photo seems a little over exposed to me.
4) Try using a larger f/stop (smaller number, (f/4.0) to help blur the background (eliminate folds and fabric texture)
5) Try using a light pointed at the back of your subjects head to provide some rim lighting.
6) Work with your fixed lighting (non strobe) first as it is generally easier to adjust and modify (unless you understand your strobe's manual settings and can dependably trigger it remotely.)
7) Experiment and experiment until you find the look YOU want and like. That is the best way to learn.

Good luck and keep on trying until you develop a style you like and can control.