I don't remember ever being easily excited, as an infant I only cried when I was hungry or in pain, as a small child I'd usually prefer drawing or playing alone, etc... I never saw the appeal of playing games, and kept waiting for the other kids to grow out of this, which of course never happened (and never will). I never felt a strong emotional connection to my mother, she was just my main "safe person".
I've never made the conscious effort to avoid emotions, or connections with other people... But I've never felt that profound connection to people since I lost contact with my best friend when I was around 10 years old, and my grandfather died a year later. I mourned both losses for a few years, I think mostly because I just couldn't seem to connect with people anymore, so I was left feeling extremely lonely. The reason I lost this friend was probably my increasing inability to express how I felt, giving the impression that I didn't care about our friendship. I'm not sure whether my inability to connect caused my social anxiety, or whether my anxiety kept me from connecting with people, either way it started around this age.
Since then, "friends" have come and gone, and I haven't really cared much. I never really loved them, it was more that I just didn't want to be all alone. I've also been feeling increasingly uncomfortable and numb around my family members since around this age. And of course, my ability to get excited about things hasn't exactly increased over the years.
I DO experience emotions, just not about other people. In relation to people, I only feel discomfort, anxiety, and my self-esteem going up or down according to how they feel about me. It's not that I don't have feelings, I just don't get those feelings about other people, they always revolve around me and my self-esteem. How others make me feel, about me. If they're obviously very fond of me, I might hang around them on occasion because they make me feel good about myself, not because I have "loving" feelings towards them. So I guess in that way, I'm extremely egocentric, without being a narcissist in any way.
My bouts of depression have probably come more from a wish of just being normal, and losing hope that this would ever happen, than anything else. At least since the age of 16 or so. I'm not lonely anymore... I guess this could be a defense mechanism, though I'm not really sure that I care... I'm more content now than I was, so why would I want to go back to feeling like that? The main thing I'd like to improve is my self-esteem and "sense of self", maybe that would make me more inclined to be social, or maybe it would make me even more of a recluse because I don't need positive attention from others to feel good about myself. I have no idea.