Wow, you really like to jump in the deep end! That's a tough shot to nail and you've done a good job to get started.
Strobe positioning is tough but fundamental, so it's important to get comfortable with early in your shooting, so I would start there. You can practice at home on land even. Also try to visualise the cone of light coming from each of your strobes. Once underwater, turn the camera to face you and take a few moments to picture how the light is going to spill from your strobes and reposition them. Obviously you will need to tweak them as you create shots, but knowing what your "base" setting is will make that faster in practice as well as helping you to understand what will happen in a given situation more quickly.
If I were taking that shot, my shutter would be considerably higher than 1/60 to keep the background darker and hopefully not blow that left hand corner as much. Making the aperture smaller would also help, as has been pointed out.
It doesn't look like you were getting any rays from the sun in those conditions (you can see them with your eye alone most of the time) so I might have even moved positions slightly to eliminate some or all of the sun as all it was going to do was add a big bright blurb.
Still nice captures and I do look forward to seeing more shots!
Obviously this is a situation where I should have bracketed my shutter speeds. This is the original RAW file to give you an idea of the colour when taken.
