Need help

I been taking oxy 40s from 15-18. I am 18 right now, I got to the point I can take the cold turkey withdrawal head first and get out of the withdrawal pain and come back to it couple days after I go through all that pain and repeat it over and over. I’ve not taken any other drugs beside oxy, codiene, and weed. I am not planning to take anything else either. I’m not planning on rehab or Suboxone since I really believe I can do it without. I can’t stay off oxy more than a week. Don’t know what to do anymore. Can anyone older talk some sense into me. I don’t even care about the cold turkey pain anymore. I just want to stop coming back.