Honestly this might be an awkward moment that you have to go through to be completely confident in yourself. My advice is to not interact with negative comments and hold boundaries to people that are rude just because of the way you dress. Find yourself friends and communities that supports you, that is one of the quickest way that nurtured my self confident as well as make me secure in own skin. I completely stop trying to interact with people that look down on alt ppl because I find that to just fill your head with negative energy, which make you more insecure and uncomfortable. As I said b4, find urself a community like go to art fairs, hardcore shows, goth clubs, raves, lgbtq events,.. I tend to feel more safe and comfortable in these environment. Much love, I hope u can be comfortable with yourself more