You might not know. Not really. Imposter syndrome in the PM world is a big challenge. I have it myself but a birds-eye view tells me I have done a really good job for the most part.
Treat yourself like a product. Ask for feedback on your own performance. Ask thoughtful questions when you get feedback that isn't positive. Dig into the positive feedback too. Make sure you are working in a way that allows for honest, transparent feedback from both sides. And when you get feedback that isn't great, try not to be reactive and defensive. Understand it. Grow from it.
Are you not getting promoted and feel that you should be? Ask for clear guidance on what you need to work on to move to the next level. Do your research on what other PM levels are responsible for and compare yourself - use that as ammo if you are already crushing those skills.
Have a great relationship with your engineering and design counterparts. Get their feedback. Make sure you're tying metrics to problems you have solved and are showing how they are moving. Are you moving the larger, northstar/OKR, metrics forward? Show that.
All in all, you're doing amazing ;)