I did a quick look through of your gallery & your stuff is very interesting. I like how clean everything is, I'm a stickler for neat & tidy. But if you don't mind me laying some crits on you - I've noticed you have a good eye for posing, very sexy. But The number one thing that sticks out to me, that can hurt these poses & a finished piece is lack of thrust. In figure drawing, a thrust is considered the movement, emotion & base of any pose. The thrust really consists of the head, ribcage & pelvis. If you look at any book by Victor Perard, he demonstrates all different forms of figure drawing. I suggest studying his exercises & even doing some yourself! It will really add some movement into your figures. In my personal opinion, a more dramatic figure, is a sexier one.
With that noted, it's always FANTASTIC to play up on dramatics! Coloring, shading, lighting, line boldness, composition, etc. So what if you can draw the figure getting penetrated? Yes, it's sexy. But let's push it further & really captivate our audience, make their spine tingle & eyes scan every inch of your drawing. That's not to say that every drawing has to be dark & moody lit by candlelight, etc. But you have some great opportunities to try things! Take this piece for instance; perhaps you can go back into the lineart & try colouring it again, for practice of course - & this time imagine the light coming from the bottom of the picture. Really THINK about the 'shapes of shadows' - what abstract shapes can you add into the shadows? This will make your piece carry further. Play with colours as well! This is a very cool colored pallete you've chosen, try adding some warm colours to not only add contrast, but 'heat it up'.
I could yank on you about anatomy, but it really just takes practice - if you look at Perard's work as I had mentioned & practice. You'll be surprised how much you pick up when you attempt to draw again. It's all about having a good eye. If you're really interested in anatomy however, I suggest picking up a copy of Richer's Artistic Anatomy. He explains the entire body wonderfully. If you're more of a visual learner, I suggest looking at any book by Burt Hogarth (Dynamic Anatomy is a good one.)
I guess all I can really stress is just practice, you have potential & a good eye for sexy. Keep at it! (: