I feel the exact same way. When I have 1:1s with my manager the topic of career progression often comes up and I kinda feel bad saying I'm perfectly happy as a sr engineer who is dependable and does good work.
I think of it as there are 2 ways to grow your career. Vertical and Horizontal. Vertical growth is another name for promotions. It involves having more people reporting to you. Horizontal growth is gaining new skills/technologies/knowledge/etc. I prefer the second, and so far my company has rewarded me financially for doing so.
Hey, you do you! If you have reached equilibrium in that you are happy and fulfilled and also a productive member of the team, that seems great for all parties involved.