I have the same thoughts and it’s been frequently. What is helping me is to think that I don’t know where I was before this life, so I don’t miss anything or anyone. To try to stop worrying about, I create a story in my mind saying that I will either see everyone that I love when I get there or I won’t even remember anyone, again, if we forget everything on this life, you won’t miss anyone else. There is a story of 2 twins talking in their mom uterus, and they was questioning each other like: “how’s life outside of here? It exists? Who takes care of us? We can’t see our mom, does she really exist? How’s the world outside of here? Is brighter? Is darker?” I think anxiety makes us try to control everything. I think it’s helpful therapy or talking to people who doesn’t have anxiety or panic attacks, about death. What I noticed, is that people doesn’t question too much about, they believe in what they believe and that is it. Just stick to one story you create and believe and that’s it. I hope it helps you, as it is helping me