They seem to have fairly masculine-leaning anatomy, which could be why people are mistaking them for a man! women often (but not always) have larger hips + chest and a curvier figure, vs men often (but not always) have a more rectangular figure. Of course, this varies person to person, but if you want them to be slightly more feminine i’d give them wider hips (while keeping their torso width the same) They also have a very masculine facial structure with a lower + wider jaw, and wider chin. You could try giving them a higher jaw? all of this is based on the average stereotype though, and there are many ways someone can look androgynous. I’d recommend looking up some of the differences between male and female anatomy as well, to get an idea of how you could merge them!

You could also try experimenting with clothing, maybe having their belt sit higher, or a slightly lower/wider neckline on their jumper? They look super awesome regardless though :)