I am sorry that you are feeling uncomfortable with this situation. Unfortunately having an early development, especially in AFAB (assigned female at birth) people can be tricky. You do have a right to be concerned, and I want to validate that concern. It is very likely that these men are initially interested in you sexually, but probably do realize you are a minor and that's why they look away quickly. Sometimes they may be drawn to your figure and don't realize you're so young. It is, however, unfortunately possible they may not care, and are attracted to you anyway. It's gross, but I wouldn't be surprised. I encountered it as a teen myself and it felt gross to me, so I commiserate.

I want to say that you should actually be most wary of those who are extra nice to you. Those are, mostly likely, the ones who are into you. Men often act charming or chivalrous when they have ulterior motives. Not always, and I am not saying don't trust anyone who is kind to you, polite, or does nice things for you. But be discerning, and be cautious, especially if they are adult men, and not minors like you. An adult man has no business being super interested or invested in a teenage girl. Those are not safe people. So just be careful.

My hope, too, is that this doesn't cause discomfort with how you feel about your own body. I know it can be hard to be fully developed when your friends aren't yet, or feel uncomfortable when older men are obviously attracted to you; however, it doesn't mean it's bad or your body is weird or you should feel self-conscious and ashamed. You are okay the way you are, and it's important not to let others' judgments influence how you feel about yourself. You deserve to be healthy and honor your body. We all deserve that for our own bodies. So be kind to yourself. You're okay the way you are.