I read your whole post and I can't say I have good advise. You seem to be well aware of addiction and it's dangers. If you are on Sub then there is some history there.

I am really questioning why you are being prescribed an amphetamine if it gets you wired. My understanding is that stimulants should only be prescribed for ADHD and they have the opposite effect of calming and focusing. I am not ADHD so I dunno. I was however badly addicted to meth for five years and withdrawals were not pretty at all. This was five years of heavy meth use and the withdrawal took over a year for my brain chemistry to get back to normal. They would not even let me work during that time. I was inpatient for three weeks and then on halidol for a year. They took my drivers license for 6 months. I wasn't suffering because I was flying high on a post acute withdrawal that caused a full blown manic episode.

I think my advice is to tell your prescribing doc to cut you off the amphetamines. You don't need them and they are dangerous to you. My normal withdrawal time to get back to normal after a period of heavy use was two weeks. I can't really say what happened for sure when I went into that year long thing when I got sober. I do remember clearly that in two weeks of not using meth and sleeping a lot I would feel like my real self. This is when I would pick up again. I think tackle the amphetamines first and then work on the Sub. My two cents.