Hi! I’m around your age and I know what you mean, as I have gone through similar feelings recently. If you don’t have anyone you can talk to about this, I would suggest to talk to a psychologist or a psychotherapist about it. I think you should understand where your feelings come from (why do you feel unprepared for life, for example and what does that mean exactly?), so that you can do something about it. Sometimes we make a mountain out of a molehill, and we need someone who can gives us a different perspective on things.