I was a similar situation for a long time OP. Went to rehab court-ordered rehab once and literally snorted an 80 of oxy the day I walked out. After I spent awhile going one week on one week off until I was just like "alright enough of this shit, I need to do something". I really wanted to stop doing them but yeah something just kept bringing me back. I decided to go on suboxone, which at first I believed was a 'miracle drug', now I just realize it kept me doped up enough to stay clean for over a year at least.
Sure enough I slipped back into my old ways, this time though it was more like binges of fentanyl/heroin and going back on suboxone. Let me tell you, it fucking sucks to go through that precipitated w/d constantly. I would time it so I would pop 4mg under my tongue just before sleeping and basically slept through the precipitated w/d, or set an alarm at 4am, wake up, put the sub under my tongue, then immediately go back to sleep. I found as long as I didn't binge massive amounts of fentanyl, a strong dose of suboxone would precipitate w/d for roughly 2-3 hours, and I wouldn't feel anything. Massive fentanyl binges would create 2 day w/d regardless of anything. This was actually a little harder than it sounds, and many times I waited too long and woke up with the sub beside my head from not taking it. At one point I would make my gf put it under my tongue for me. If you take it to early, get ready for precipitated w/d hell with no hope of sleep.
I was working a really good job through all this (that I still have, miracle that I didn't tank that), but was always fucking broke. Tired of being broke along with the constant ups and downs really pushed me to cut all that shit out entirely. It took a good 2 years of on/off use but I got through it. I dropped my dose from 8mg to 2mg by myself in less than 2 months. I walked in my doctor's office one day and just told him to prescribe me 2mg (he was a little shocked). I think I've done opiates 2 nights in the past 1.5 years and I just lost the will to do them. I seriously don't give a fuck about them anymore, and taking .5mg of suboxone 2-3 times a day now. It's actually a bitch to reduce your dose below 2mg without any discomfort, which is why it's taken me a good 4 months just to go from 1mg x 2 daily to .5mg x 2/3 daily. To be frank I actually want my doc to give me like codeine or something instead to wean off (to anyone going to say "oh codeine is still addictive", fuck you, codeine doesn't do SHIT to anyone who's used to fentanyl). In hindsight, I sorta wish I didn't get on the subs, but I also know I would have probably never really quit, or at the very least, I would never have lost the desire to do them.
I expect methadone would have a similar effect, except you'd have almost no motivation to stop. Buprenorphine on the other hand, eventually you just don't care.
Edit: Also, the fact of 'growing up' and the desire to join the 'real world' is also another big motivating factor to steer clear. When I was younger I was so focused on school and drugs, when school stopped, I was focused on getting a job and drugs. You need to break that focus on drugs mentality. I recently read an article explaining that the reason we are able to walk by homeless people in misery without a thought is because they don't elicit an emotional response; ie, they do not register as 'human beings' in our brains. The article also stated this is the same reaction people have to drug addicts. If people in general think of you as a drug addict, they will literally not give a shit about you, and try to avoid you at all costs. The only people you can remain close with are other drug addicts, since they still view you the same. You really need to break this cycle and join the real world. At that point, you will start to look at drug addicts the same way (albeit with a little more understanding). It sucks, but that's what needs to happen to be successful, lest you remain in a state of perpetual monotony. That's what I imagine happens to people who remain drug addicts all throughout adulthood; at some point, you become almost permanently branded, and you are fucked for life. The only people who will see you are other drug addicts, and the cycle continues, for years, until you die.
On the flipside though, I find taking small doses of amphetamine, a lot of people don't really give a fuck. As long as your productive, do your work properly, don't look tweaked the fuck out, people tend to be more lenient (or ignorant). The same cannot be said for heroin I'm afraid. You may be good and productive for some time, but eventually the drug/sickness/appearance will catch up. I guess the same will be true of amphetamine, but I find amphetamine to be much more manageable/less addictive. Taking too much amphetamine will just bring about the negative side effects, and tolerance develops to the point where again, I don't want/feel the need to take more. Even if i take it every day for awhile, I might feel 'off' for a day or two but that's it. I'm talking doses of like 20-30mg here, nothing crazy...
Sorry for the rant, as you can guess from my past couple paragraphs, I took 30mg Vyvanse earlier today. Sounds a little hypocritical I know, but opiates are on a totally different spectrum than d-amp. Also, don't take meth, you cannot function and look normal on that shit; it's too intense.