Is it normal to feel like an emotionless machine as a social defense?

I served in the United States Marine Corp for four years and that may be an issues as it pertains to me specific dilemna. Most people I know would say that it is a joy to be around me. I'm the life of the party, I'm flamboyant. Great sense of humor and I can talk my into and out of any situation. Looking at me from a third person perspective you could describe me as vibrant, alive and wonderful. However I feel far from it.

In large crowded areas I unconscioulsy observe every person in view. Height, weight, eye color, and what they are doing with their hands. Simply based on what a person looks like and the scent of their breath I can sort of cameleon my way into a conversation with them. I can smile and at times it actually feels like I mean it. But there are a few discrepencies with my life.

I'm a work-aholic. I don't go out much because it doesn't seem practical to me. I'm a beast of routine, I eat at the same places and I drink the same drinks. But I will try anything once.

I would classify my personality as being very intense. I commmonly ponder the meaning of life and the underlying eccentricities of other people. Some would say I'm an old soul but I'm not that old, young by most standards.

It has been my experience that through interaction with other people ,especially socially, that equal amounts of mental pain follow and good that may come of any relationships. I prefer my own company but I long for social interaction. However, every encounter that I have thus far experienced has ended in pain and contempt at my expense.

Don't misunderstand. I have more empathy that most of the people that I know. Through my military experiences I have seen things that have horrified and humbled me. With this feeling intend to further my education towards a career centered on direct intervention with hopless cases in society.

At times it feels like an obsessive tick where I can smile and one point and then feel nothing and do things that I would not normally do. The way that I perceive this problem is that I've experienced so much pain and personal anguish in such a short amount of time that it may have become some sort of post traumatic stress disorder.

Self prognosis if sketchy at best as I've read so any feed back would be greatly appreciated.