Welcome (again) Chris.
That is an awful situation to be in. You can't really depend on your parents, and yet you are dependent on them, to get to work etc.. As you noted the drugs are complicating matters a bit, as they are still in your system. You may not be able to pass the tests at the current moment. But you will get there!
I think you have already taken the first, most important steps. You realise the current situation is not good for you, and want to do something about it. And as easy as it is to write words making it look like these steps are simple, they are anything but.
As Duke suggested, a change of scenery may improve things for you. It is also much harder to resist drugs and other substances when you are in the middle of a bad situation. You would be getting out of the toxic relationship dynamics of your parents, and find a job there.
I personally think sanity is one of the most valuable assets. One which money can't buy. So please look into options to move out.