I agree with paul, you may adjust the "levels" with photoshop or another ımage processing tool like GIMP, you will get satisfied more with your work, unless this is not your style or choice :).
I am waiting more from you.
(By the way i love the girls in your bridgestone photos, have you got the number :p)
This is a wonderfully framed portrait, Jonathan, but adjusting levels in Photoshop (or any image editor) does magic for shots like this. BTW, whether accidental or not, you did well to underexpose your shots. The dark details will appear when you adjust the levels. If you overexpose, however, that detail will be washed-out and lost forever.