Just a Touch of Human

I don't know what I've realised or what's forced my mood down. I think it's something to do with regret.
I don't know my future at all. I'm completely uncertain of it. I used to be very certain. Though there were certain... ideas in my mind, I didn't ever seriously think I'd act on them, even when I did attempt. I just assumed that my life would continue, I didn't really... think. Now, I may have made plans for my future, which is something I hadn't done before, and I may appear more certain, but I'm less and less sure of anything now. My moods are going from extreme to extreme within the space of a few hours. At about 4:30 today I was good; happy, jubilant and full of fulfillment. I was feeling great, and that's not even exaggerating. By 5, my mood had started decreasing. Now I'm nearly at the stage I was on the weekend. I can't focus on anything and I think a lack of sleep will be something that will feature heavily tonight. I hate this. I hate not knowing what my mood will be or whether there's chances I'll go to extremes, because I can just... never tell. I hate it. I hate it. I hate it. I want to actually have a reason to be feeling the way I do, I want to know why I'm feeling how I do, whether it be fantastic or rock bottom. Can I not justify my own feelings?
I want to know whether there's a chance I'll be gone by next month, or the month after, or by the end of the year. I want to be in control of myself. That's what I hate. Not even being able to control myself, whether it be my thoughts, actions, or feelings. I don't want to be dead and not even know the reason why I've done it, let alone having anyone else know it.
I hate this. I hate not being in control. I used to have it, I swear I did. Can someone find it and give it back? Otherwise I'm scared. Not for myself, but that I'll hurt people. That's the last thing on earth I want to do, and if I do, I want to avoid hurting them as much as I possibly can.
I need to change my mindset. I don't know where to begin. I don't want to hurt others, but neither do I want to hurt myself.