Sorry to hear. I had a lot of the same problems growing up. I was in lunch detention almost every day for misbehavior. I didn’t behave the way I did to harm anyone else, I just found school to be very boring. With ADHD, every behavior happens for a reason. ADHD has a very potent curiosity when it comes to things a child takes extreme fascination in. This is why we see thrill-seeking or immediate gratification oriented behaviors. There are some other, less-severe behaviors, that are exhibited more to obtain a reaction from the parent or other person in the child’s vicinity. These behaviors deal with the inattentive part of the condition: we with ADHD get bored easily and then start looking for attention in the form of misbehavior. Every behavior happens for a reason. For the thrill-seeking behaviors, it’s important to spot the source of the curiosity and fascination. For attention-seeking, it’s best to ignore and be non-reactive.
Hope this helps, I have some programs on ADHD parenting if anyone would like some insight.