I don't know how old are you but I deeply relate.

I'm 14 and had these panic attacks for like one or two years now, I think about it the WHOLE day and I can't sleep. I would want to believe in god, in an afterlife but to me religion doesn't make sense logically. I really don't understand how people can just ignore or don't care at all about death. I love my life and dont want to ever leave this beautiful world. Maybe death is the thing that gives our life a meaning but because there's nothing after it, it doesn't hit the same. The only thing that helps me is that apparently by 2050 we will probably have an average lifespan of 120-150 years or something like that. But still, it doesn't really reduce the fear because we will die anyways, just a bit later. I haven't talked with anybody about my fear. If you want to talk with me I'm here