It is totally normal, I experienced the same things when I was younger but trust me, you will get over it!
You're perplexed by the complexity of living man, I've been there. There are so many variables and everything seems out of control, so all of your questions are directed towards figuring this puzzle out.
How to do this, but what if that happens, then how would it affect the third thing. This goes on forever, until you don't have the energy anymore and you just shut down. It's kind of like having a personal torturer at your disposable..
You can't control life man, it's an illusion. All you can do is decide what you want and then see how life gives you clues on how to get it. Decide who you want to meet and then look around for the bread crumbs life is leaving along the way.
What you focus on, your reticular activating system is like a heat seeking missile - it will find a way from the smallest clue, don't worry.
Here are some videos that should help you with this:
Hope I helped there. You'll overcome this and when you do..all the heaviness will be gone and you'll feel like a freaking bird, trust me on this one!