I look really immature and it makes me feel terrible?

okay lately I have been feeling really down about how I look but like, it's not just about how I look. I don't have an issue with my body shape or face or hair or legs or anything like that, I've learnt to accept that stuff. but it's just like, I'm really... small. I'm really short, people often when we're talking they're just like "you're so short!" I don't know exactly my height but it's tiny, I'm like the 4th shortest in my year. my boobs are also really small like an A cup and they're really far apart so I can't even get cleavage with a pushup bra. my face is also really youthful and young looking. all of these things I wouldn't mind by themselves but together they just make me look really young and immature. I'm 16 and a lot of people often think I'm 12-14. I have no hope of lying about my age to get into clubs and stuff like my friends because I just don't look old enough. this has really been getting me down lately, I feel like I'm too immature and that I need to grow up but I don't know how/ what to do. I know that when I'm older I'll appreciate it and stuff but for now it's really hurting me. my friends always joke about me being so small and not having boobs. girls are always complaining about being 'fat' and stuff like that and it's just like, at least you actually look like a woman, I just feel like a little kid all the time.