I had similar fears and traumas in my teens over The Rapture etc.
Occasionally teens would joke about such thoughts and feelings. But it was rarely a joking matter, to me.
I took comfort in the fact that salvation is forever, and knowing that sin will always happen, even as a Christian..that’s how I got through it. I realize that not everyone believes that way, but that’s how I interpreted it as a teen and now. After numerous bible studies, my interpretation has not wavered.
By the way, I’m not suggesting that by not losing one’s salvation, one has a free ride to do whatever they want. :-p That’s another aspect of one’s relationship with the Lord...a lot of facets, etc..