We are human and obviously, we made many mistakes. Some decisions might help us to enjoy a better life but who knows if you are already enjoying it even if you think it is a mistake. It's really hard to say because nobody knows the future. I think we can focus on our present because it can change the future but thinking about the past for regretting is not good but we can consider it as a lesson.
As in ehn.... no one knows the future, we also don't know what could have been ifnwe made different choices. So we should simply be content with our reality and move on from there.