[Kris]

Don't forget that besides the technical skills it is also mental. Even a bigger opponent will be intimidated if you put on a stone face an attack with no fear. I am 173 cm 67 kg and have the same experience as you. My sensei here in Japan is 165 cm 62 kg and there is no way me or any other fighter will win over him only because of size. A shorter fighter will have to scare the bigger fighter just to level the playing field, that is my take on it.