Recording w/ a Steel Series USB headset on MacBook Pro 2012

I bought a MacBook Pro in Feb. of 2013 but am pretty sure its a 2012 model, there is no audio out head phone jack no hdmi and has a dvd drive in it to give you a idea of what model it is.

I want to record audio from my steel series headset and use the mic to record my voice, I am recording all of this for my stream on twitch, the other programs that are in use are adobe flash encoder and Cam twist, I played with soundflower and midi audio but both don't work, I can only get mic no audio from gameplay or anything. I would ideally would love to record myself playing and talking over games using my headset without having to disturb others around me when I record any help please I've tried everything.