When I was younger I too was convinced I would not live past 21. I went off the rails at 17 as I thought I didnt have much longer to live, and just party party partied. When I didnt die at 21 I fell into a deep depression which had me hospitalised for a number of months. I was in limbo a few years after that, not knowing what to do.

I have predictive dreams and very vivid dreams, that do come true about half the time. I had dreams before 21, that I had hoped were predictive dreams, about my death but it never happened.

I dont know if this is helpful to you, but know you are not alone.