Is it normal that i always feel despair?

Okay... Yes, I am a woman. No, it's not hormones, because I've felt this way MY WHOLE LIFE. Everyday I have a fear of losing interest in people, hobbies, activities, etc. I always feel some level of despair in the pit of my stomach, and sometimes it gets so bad that I have to lie down, curl up in a ball and hug myself, and shut my eyes until it passes. No, I promise you this isn't hormones. This has been going on since I was a child. I've tried to talk to my parents about it, but they assure me that it is completely normal. I feel like I will never be happy in my life. You know, I don't even want to be happy. I just want to be content. Or interested in something. I fear even the slightest change, thinking that any level of joy I experience will be torn away from me. I've lived my life like this. I'm sick of the never-ending despair that makes me hurt so bad, sometimes I can't even concentrate in class, the anxiety that makes it impossible for me to get close to anyone, and this hell that's dominated my life. I feel hollow. It's like I feel nothing. I could kill somebody and feel nothing. I understand this completely. I've planned on how to kill members of my family before just for the fun of it. And felt nothing. And just to let you know... My childhood did suck big ones. Any help?