Hi Kristin. Many of us have been in your shoes. I know I have, I can remember three hospital visits of my own right off the top of my head. As anyone with health anxiety will tell you, the doubts start creeping in the second the doctor stops talking. That little voice in your head that says, "Nope, he/she is wrong. I'm dead, it's as simple as that." Therefore, our goal as health anxiety sufferers is fairly straightforward. You need to believe the diagnosis. I know that's hard, and I know that doctors miss things. In my case, I've been tested so much (hypertested, as one doc put it. thanks.) that it's very, very unlikely they've missed something. I need to be OK with that. Truly, nothing is guaranteed to us. Once you come to realize that is your real challenge, things start to get better. Attacking the real problem. One thing I try to do is tell myself, "Well, here we go again, the same issue I experienced 3 (days, weeks, months, years) ago. It didn't kill me then. I have a clean bill of health, there's no reason it will kill me now.
Others on this board can state it more eloquently than me, but that's the common theme. You need to be OK with the diagnosis. Only than can you start putting the pieces back together.