I'm on my phone so sorry for the short notes. Mirtazapine (Remeron) is not going to fix your issues with Opioids man. I'm all about optimism and open-mindedness, but I gotta tell you how I feel. I've gotten to know you through your posts and I have your back.
I am all for people making attempts on their own at fixing these problems. I see you going up and down and it's a shitty cycle to be in .
I really think you should consider Buprenorphine. I'm thinking ~2mg per day, either once or divided in two. You continue doing everything else that you've done up until now to string your days together but with a little extra help to get you over the humps.
We can get youset up with volumetric dosing and have you drop by 0.1mg every other day which would have you at zero within 40 days. You will feel almost no withdrawal going down at this rate.
I know everyone hears maintenance drugs and feels like that is the "nuclear option". A lot of these people are too afraid to make a radical decision like this and they instead get caught up in cycles like yours.
If you want my advice that's it. I truly believe this is your best chance at fixing this. Please consider it. I'll help you through the whole thing.