I'm so stoic that I think I have a mental problem

Hi, I'm a teenager, and since I was little, I've been aware of what's going on around me and about reality. These days, nothing affects me. When I was told my grandfather died (I had a good, close relationship with him), I had to pretend to be sad, but in reality, I simply didn't feel anything. I understood and moved on. I felt strange, and it was the first time I questioned why I didn't feel those emotions like normal people. When I found out my neighbor, who was my age, died in a car accident, I didn't feel any grief or sadness at all. I'm starting to think I'm depressed and I'm not even aware of it, or that I'm literally autistic because I don't manage my emotions well, lol.

Does this happen to anyone else, or is this normal?