there is no dress code for anarchists. what people think of you based on how you dress has nothing to do with whether you (or they) are anarchist or not.
questions of style and how people fit into groups (or don't) is more a social question than one that is political (for lack of a better word). social questions are meaningful, of course, and involve all kinds of facets, like language, clothing, hair style, etc. if you don't fit in to whatever anarchist group you have found, then you can see if people actually care (or if your uneasiness is your projection), take time to build relationships, do stuff online, and/or try to meet anarchists who might not be as easily identifiable (not all anarchists dress in black, as you yourself may be proof of).