My credentials for answering this question?
I have an college degree in psychology, (but I’ll admit I have never worked as such). Plus, I am a lot like you. Plus, I read a lot an remember things that interested me because i felt they applied to me.
That said, I remembered your OP when I recently read Daniel Goleman’s best-selling book: “Emotional Intelligence”.
In that book (chapter 2.5) he describes a fairly common kind of people (1 in 6!) he labelled “indisturbables”. The phenomenon has been researched by Daniel Weinberger, now psychologist at case Western Reserve University, and Richard Davidson, University of Wisconsin.
Indisturbables experience seldom and few negative emotions, but they do experience positive ones. Actually even in their “neutral” position (just sitting and doing nothing) their brain is more cheerful (as measured in parts of the brain activated, levels of transmitters and hormones etc) then average. Also, these people have a distinct positive outlook om life, and a lot of ideas and theories to support that outlook verbally. These people tend to be typical left-hemisphere people: verbal, logical, rational. (as opposed to spatial, musical, emotional)
These indisturbables show all the fysiological signs in their bodies when feeling emotions like despair, anger and fear, but these emotions do not reach their brain. Their brains actually show all the signs of indisturbable coolness. (and that is the big difference with alexithimy, where both body and brain panic, but the person does not have the words for them, see below). It seems the brains of indisturbables quickly and effectively ban out negative emotion (so it stays in the the unemotional left hemisphere) or immediately and subconsciously counter it with positive thoughts about the situation.
The researchers mentioned have not yet found out it it’s genetic or learned. They also cannot seem to find anything wrong with it, it seems an highly effective way to deal with negative emotion. We only do not know how much it affects self-awareness (and if that is is a good or bad thing in itself).
Goleman also describes another condition. (chapter 2.4) known as “alexithimy” (I do not know how to anglifiy that word). From the OP, I do not think you have that condition, but it may be worth reading about.
Basically people with alexithimy experience no feelings at all. Fysiologically, the show all the signs of emotion, both in their bodies and in their brains. But they do not recognize the emotions as emotions. They have not much of an internal life and have dull or non-exitent dreams at night and fanatasies at day. People like that somatize: the think they’ve got a belly-ache when they are afraid, for instance.
People like these are not, as you describe yourself, usually happy. They are dull, colorless, an usually described as “boring to the point of driving other people mad”. These are the kind of husbands sent into therapy by their wifes.