Haven't seen your port but from your avatar I think the model's expression looks a little introspective, like she's thinking about something maybe. Some people who are more into dramatic facial expressions can think this looks like a blank face, like the model was just bored and staring at nothing.
I do a lot of lingerie and nudes, so I mostly make a smirky flirty face, sultry face, angry sexy face (this is requested a lot but I'm sick of it), and there's more like innocent girly face, and so on. I have pretty much nailed the pin up faces.
At a recent shoot I did a snobby, stuck up look which was fun. Sort of looking down my nose with my chin up.
I don't often get asked to do an emotion. I mostly get asked to make a certain face and that's the face I do, but I do like it when I get to be somebody besides the sex kitten every once in a while.