I can relate to that some. I finished my engineering degree a year ago and I've been at my new job almost a year. I like the job and it will be a solid start to a career if I stay in the field, but there is a small part of me that thinks I should be doing bigger and better things that I should love. But I haven't found that bigger better thing. I don't worry about whether my degree was worthwhile. My job is good for me now, and I'm trying to get as much experience as I can from it for now. I know plenty of people who have changed careers after decades, so if I find a passion I will probably be able to turn it into a career. I think the biggest problem in my situation is procrastination. I don't know what I will really love doing because whenever I find something interesting, I just make vague plans and never follow through. I think if I start making this kind of change in myself, I should be able to do better with the job I have, finding something better might be easier, and making changes will be easier. Sorry if this doesn't really reflect your situation, but your comment felt similar to me and it feels good to put all that in writing sometimes.I'm not sure what my "true" passion is, I wonder if I'll ever know.
I think the fact that you like your job is really important. Don't close off the adventurous side of yourself, though, when it comes to opportunities. I feel like our generation, the millennials, are so accustomed to those success-stories of very young people that we feel less-than when we're not rockstars or billionaires or whatever.