I don’t know how your thoughts are about medication ? But both ADHD and depression can respond well on medication.
My youngest is now also diagnosed withe severe ADHD combined type. The most important strategy is never to join the chaos when they’re overwhelmed. Stay calm yourself and offer structure and calming strategies. Occupational therapy and psychological support can be helpful as well as a good pediatrician. Sensory motor therapy can be a good one too

Think you need to go back to your specialist (assuming you have one) and ask for a referral for a good psychologist who can help you with how to deal with the behaviour. This is just as much for yourself as it’s for your son.
My friends daughter goes to a special school where they get therapy and education. There must also be lots of ADHD groups out there, I would certainly find out where they are and connect yourself and your son to a group.

He needs some sort of structure in his life, whether it be work, sport, army reserve etc. I would speak to your GP about possible solutions.

Is your son seeing a medical professional who specialises in ADHD on a regular basis? Are you able to speak to him / her at all. Is there a support group in your state at all? I don’t know where you live but I believe there is one in Adelaide. Other states often start groups before SA does. In Adelaide there is a set-up called Fourth Story. I’m not sure whether it is in a school building ot where it is. A girl I knew went to one. Places like YMCA may have activites. Your Local Council may have a list of groups / activities in your area.

yeah i think that he needs to be wary of his actions, (a lot harder with adhd). maybe try to get him into work so he can start learning some skills

That is very hard on you as a parent especially having ADHD where their energy levels are high . My sister in law has a 15 daughter who has anxiety and does not listen to her until she learns it the hard way . She does tell me perserverence and routine discipline works for her such as grounding if she goes to far , banning from her PC games etc… . In your case I would also seek a specialist who specialises in ADHD and see how you go . Hope you get some good support

Does he have a youth worker/counsellor? I would suggest this as a step as it does help youth to have many supports in place. His GP is a good source for linking with other professionals and as he has depression the GP should have a plan in place.