On hormones and happiness

I can't really explain my feelings. All I can give are vague generalities: I feel very depressed. I feel extremely insecure. I want to disconnect from everyone. I feel like it's the only way to get out of this funk. People seem to only make me more depressed. Thinking about them, being with them. I know that my feelings are turning into a self-fulfilling prophecy. I can't express myself, can't articulate. My brain is a muddle and I feel too insecure to even attempt expression most of the time. The depression is cyclical and I've been sucked into the middle of a whirlwind of emotions that feels out of my control at this point. Is this just pms? I'm to the point where all I'm going to be able to do is lay in bed. I don't want to talk to anyone. I don't want to see anyone or go out with them. I feel weak and pathetic- do I have any reason to feel this way? Why can't I make it go away? Who runs this body? What makes us happy? There's some philosophy that tells us only we can make ourselves happy, we must take responsibility for our happiness, it's only possible when we have the "right" outlook. But I wonder about these assertions. Our happiness is often controlled by simple hormone cycles, chemicals. I used to adopt so adamantly the first mentioned life philosophy, but now I'm trying to find a balance. Happiness is chemical. The nature versus nurture debate/balance can apply to specifics such as happiness. Nature vs. nurture; genetics vs. choice; chemical vs. circumstantial; uncontrollable vs. controllable. How much is in our control? At the same time, I'm drawn back to lessons learned from existentialism and practicality. What's the point of asking that question? If there's nothing I can do about the chemical aspect, I'm not going to deny that I can't do anything at all. Although I must say, it most certainly feels that way at times like these... fucking hormones.