Rather than the size, It's the shape of the end of your chin - and that is as important as the size being the masculine/feminine determiner / If your chin rounds off succinctly or 'squares off' (masculine). You should put on your photographs into Photoshop and do some experimentation with the liquify tool. I have a very small jawline and chin that fit feminine proportions, and when I experiment with the liquefy tool round off the squaring it makes a dramatically feminizing difference to my overall face.