You need to trust yourself. So can you?
Using is obvious, as is not using?
Drug testing is degrading. It is also unhealthy especially when you already know the truth.
As you post more in the thread it seems as if more and more red flags are flying.
You have no reason to be ashamed.
The best thing you can do to insure that no matter what you will be able to make good decisions for yourself is to keep working on you. You wrote you have the tools now, so don’t forget to use them.
Take good care of yourself.