I am 31 and half, OKAY?

I am so sick of people telling me how great it is to look young. Let me tell you something, it's not that great. I have looked young all of my life. When I was little, people used to to tell me how much I would love it when I got older. I thought then that I would not be excited to look young and now I know that I am not excited. When you look young, no one ever takes you seriously. You have to work twice as hard, if not harder to prove that you are capable of accomplishing the same thing that people think a person who looks older is capable of (even if they are chronologically younger, and/or act younger). For me it is so frustrating to constantly have people telling me their "better ways" to do things and how I should be living my life. Everyone acts like I am incapable of managing anything by myself. I get so much advice on my personal life and how it should be progressing, even from perfect strangers. For example, a lady at my church lectured me for hours on how I am wasting my life away. She detailed all the things I needed to do to get by and spared no detail on how I was probably mismanaging everything I came into contact with. Now, this is important, I HAD JUST MET HER!
When I got promoted to my current position, my boss told me that people had warned him against hiring me in that position because I was not "experienced" enough. In the meantime, I have been there for four years, accomplished most of the things we do and proven myself beyond any shadow of a doubt. Yet, because of my youthful face, I am not credible.
Even my boyfriend only looked at me once when he first saw me because he thought I was too young for him. I had to pursue him (with ID in hand).
Listen, I am glad I do not look older than I am. I would like to just look my own age. So quit telling me how great it is to look young unless YOU look young and you have some great experiences to tell me about that back up your claim.