Boyfriend (30m) stressed by how young I (20f) look.

So I've been close friends with him for a couple years now. Met when I was 18 and he was a little put off with how young I was. I feel stupid saying this, but I'm very mature for my age. I get along great with people in their 20's and 30's. Have since I was 16. We get along great, treats me amazing, and is always complimenting me. He gets stressed when we go out to eat or out in public often because I look 16. He lives in a very conservative area and with a the human trafficking that's under the spotlight, he's scared people will think he's a creep. I sent him some pictures of a dorky outfit I put on and pig tails. I was teasing him about going out like this and he was joking back. Finally I said I'll wear something cute, but I actually like the pig tails. I honestly thought I looked cute in them, and I have friends that wear them sometimes. He got so stressed and was trying to tell me i can do what I want in the end, but he's so worried people are going to think he's with a high schooler. He was begging me not to. I understand, but it really hurt my feelings. People don't take me seriously often because I look so young, and I get self conscious when people still ask me what grade I'm in. I'm almost 21! It is what it is, but I don't know how to not take it so personally.