How can I know I’m truly saved?

Q: How can I know if I’m truly saved? And is it possible to lose my salvation?

The question of being saved, or of losing one’s salvation, is a pastoral one that I’d suggest you address with your church pastor in the first instance. 

I say this because some people are naturally more self-critical and have a tendency to worry, while others are much more bullish and assume everything will be all right in the end. There are potential pitfalls to both ways of thinking.