I'm sorry to hear about your ulcers. Please feel free to moan as much as you want. You have every reason to. Diabetes can be a cruel condition.
Regarding your son, it sounds like you've tried everything to help him. Does he have friends he'll listen to? If he reads around the forum, he'll see he's not the only young person rebelling against diabetes sadly. Sometimes teens will listen more to their peers than older people, especially if those older people are their parents! It must be hard watching him neglect his diabetes so much.