If you have to actually go out of your way to make it clear to people that you're enjoying your music and "really feeling it", then you must be such a terrible musician that nobody can figure it out on their own. If you look around, you will find there are as many great pianists who sat practically immobile (Horowitz, Rachmaninov, etc) as there are who swayed around, made faces, etc. (Richter, Gould for example). In the end, the only surefire way to measure how much you're involved with your music is too .. listen to the quality of the music you're making! If it's good enough, then anything else is superfluous.