Hi, Thanks for sharing your situation.
I noticed you're from Canada, and I'm not, so I don't know if you have something similar to what I've heard of hear in the US. My understanding is that schools will have bullying policies in place that they use to deal with these type of situations.
Perhaps if you don't feel you've gotten satisfaction from his teacher, you can speak with a higher authority, like the principal. Not sure if there would be anyone in between.
The martial arts idea sounds like a good one to build self-confidence. Hope that will help.
I just read your public profile and noticed you are married. I'm wondering if your husband is giving his input in the matter, as you only spoke of youself.
I know it's small in comparison, my son played basketball for many years growing up. Well one year, he ran into a boy who was always on his case for no apparent reason. He would turn my son's name into the feminine version of the name, and that is what he would ALWAYS call my son. (what I mean is, if my son's name was Stephen, he would have called him Stephanie, I'm choosing not to use his real name, since he's also a member here.) It would embarass him when this boy would do this every time, and the other kid knew it.
He did also get threatened with violence by another kid who he had never even seen before. I spoke with the director of the sports department at the YMCA and it turned out the kid was known for causing trouble and they were trying to work with him. But anytime this kid would run into this perfect stranger (my son) he'd try to hurt him - for what reason, I'll never know.
But at least my son's situations were limited to his sports involvement. Most years things would go along without any incident, we' just run into the occasional bad apple.
I wouldn't rule out alternatives. Sometimes the particular situation is not good and is different elsewhere.
We are a home schooling family and would be happy to give you input about it, if you'd ever like it. But I also know that's not an alternative that works for everyone.
As I mentioned above, even home schoolers aren't immune from this type of thing in some situations. That boy who threatened my son didn't know him previously from school, since my son doesn't attend school, or anywhere else. They walked into try-outs on the same night, and this boy threatened my son. Figure that one out.
Please come back and give us updates on what's going on and feel free to pm me if you'd like.
God Bless your family.