Maturity?

    How does one measure maturity? I mean I look at myself, and I don't always think I'm the most mature person around. I have friends who are younger, and friends who are older, yet I see both groups with people who seem more mature than me. I'm currently 21, but mentally I think I'm younger, why im not sure. Maybe it's because for all the medical stuff I had to put life on hold, and in some ways grow up faster, yet now that things in the med field have slowed down, that part has been trying to catch up.
    I don't think age has everything to do with maturity, nor do I think anything is wrong. I'm into Disney, I like pop music, fantasy stories, I'm creative, I sometimes have trouble getting into deep discussions (but I put my two cents in when I can). People are all different, so it makes sense we're not all mature in the same areas, I also think that I'm still a kid at heart, and maybe that plays into this.
    Also with everyone in my life I've learned that another reason we're all different is because it helps us fit together, we work together, like someone's weakness could be someone else's strength, and vice versa. So I don't think there is a accurate way to measure maturity, but whether you are or not, either way your just the way you should be.