The best I ever had was a 6% full match, and the company contributed another 3% that I didn’t have to match. The result was company contributing 9% and me contributing 3%. So I agree with other comments saying you should probably be contributing about 15% total. That extra 3% doesn’t have to be in the same account though, you could open your own if you get better investment options with lower fees.
12% contribution that you don’t have to match is amazing and just make sure you’re fully vested before you take a new job. Sometimes there is a rule that those contributions are not truly yours until you’ve been at the company for a number of year.