I'm 14 years old and have been doing judo for 7 or 8 years. I've always been to defensive, never attacking enough. All of my opponents are heavier/stronger than me. I'm 5'3" and weigh 45kgs, I'm stick-thin and not very strong. Does anyone have any useful advice?
I did judo for a time when I was about your build - I came to the conclusion that as a means of exercise it's fine, but as a realistic means of handling yourself in a fight it's daft because it relies on you allowing someone to get hold of you, and if you are bigger and heavier you can just sit on your opponent and win.
Its sounds to me that if your teacher is saying "what" you should do but the "how" that he is is suggesting doesn't work for you then maybe you need a new teacher?.