I used to have this problem - where I drew the same body type, the same facial shape, etc., etc. - on nearly all of my characters. So it's a problem I've consciously tried to get away from, and with Grassblades, I hope I've made some progress:
As for gender-distribution: the top two characters in picture number two are girls, as are the two characters on the left in the bottom picture - and so is Akane, the little girl in the top picture. I've had people accidentally mis-gender both Akane and Kazue (bottom picture, far left), because they lack definite gender-markers - Akane's a six year old, and she wears blue+shorts, which I suppose confuses some people, and Kazue is very, very flatchested and slim and short, so I suppose she seems boyish, but they're definitely both girls.