Can someone with knowledge of mental disorders help me? (sorry if it's too long)

I'm not sure exactly what's wrong with me (maybe bipolar). I know most people would say I should get help and talk to a professional face to face, but that's the problem... I can't. It's not that I don't want help, I just can't talk to someone about it and it makes me uncomfortable to the point that I would rather die. I'm going to try and describe some things to see if anyone can help me understand what I have.

As a child (maybe 6-10) I was mean (I would hurt dogs and cats for example), and I don't know why... I think I wanted to kill them and it felt kind of like I was in an indescribable rage for no reason. At this stage of my life I feel terrible about it & would never hurt anything. However, I still have the crazy rage feeling where I want to hurt something but I refuse to act upon those impulses. While I was still very young, some people in my family died and when I was informed, I felt nothing even though I loved them more than the world.

In my early teen years I began to get extremely nervous and anxious (way more than a normal teen) and my heart felt like it was going to explode sometimes. I skipped school when I knew there was going to be any form of speaking or presentations because it bothered me that much. I had (and still have) trouble sleeping. Usually don't fall asleep until I can't physically stay awake any longer (sometimes 2 days). I hardly had any friends, and I currently have no friends or family because I push them out of my life by default.

Despite all this, I'm actually one of the most loving and caring people when my mind is calm. I know love and caring contradict hate and anger, but that's honestly how I am. Some days I can be happy and motivated but suddenly something will snap for no reason and I'll be either angry or sad and depressed. Every day is different and it seems like my emotions are heavy and randomly change. Starting in high school, I constantly thought about suicide because I can't figure out why I'm like this and why I can't completely control it no matter how strong my will is.

Any ideas what I could have?