What would going around looking for trouble even do? It wasn't as if Nathan would be capable of stopping everything. He only saw what he was capable of changing personally.
The problem was figuring out how without getting hurt himself like with the bus incident. Not dying or even breaking anything jumping off of that Ferris wheel was a miracle. He never wanted to do anything like that again.
Amber was a child so she was thinking like one. He couldn't be a superhero.
She thought he was cool because of his powers and his frustrating tendency to jump into the fray without realizing it was a trauma response. He wouldn't be like this at all and would go on ignoring the visions if not for what happened with their parents.
Nathan needed to snap himself out of those thoughts before he started drowning in guilt again. That was the last thing he needed today. The only family he had left was already mad at him for not going along with what she wanted.