How to level up from Mid to Senior Engineer?

Hey everyone,

I'm a mid-senior level software engineer (6 YoE), currently working at a fintech company, mostly using JVM/Go stacks. I handle my day-to-day work well, get things done efficiently, and receive good performance reviews and feedback. But despite that, I feel like I'm falling short somewhere.

A common pattern I've noticed is that during refinements or technical discussions, I don't always come up with the best solutions right away. Often, a senior engineer will propose something, and once I hear it, it seems so obvious in hindsight but I didn't think of it from the start. I can implement these solutions without issues, but I struggle to conceptualize them from scratch. And this happens more often than I'd like.

I recently interviewed at a few other companies and consistently cleared the technical rounds. But the feedback I received was along the lines of, "We are looking for more senior candidates". It made me realize there's a gap in my knowledge, but I can't quite pinpoint what exactly I'm missing.

So, I'd love to get some advice from folks who have been in a similar situation. How do you go from being a mid-level engineer to someone who truly thinks and operates like a senior? What helped you level up? Any books, strategies, or mindset shifts that made a difference?

Appreciate any insights.