she is pretty androgynous... if she just had her shirt buttoned up it would perfectly suit the tag. it's not like male androgynous characters don't have a penis and female androgynous characters don't have breasts (obviously some (most?) are flat chested but still).
Even if the shirt was buttoned up, she would still look like a girl. Her chest and waist are noticeably wider than her waist, and the way her chest is shaded is based around the fact she has breasts.