Although I have withdrawn from opiates and from Xanax, I have no experience coming off methadone. I can only share what my own experience coming off opiates has been. Like you are doing, I weaned down slowly. The closer to the end, the slower I went. And I do mean slow!! I would break the oxycodone tables into 4 pieces and then smash a piece so that I was only getting a tiny bit. When I finally felt ready, I basically just walked away... didn't have to "jump off" as I had gotten the dose down so very low.
I had withdrawal symptoms (although I chose to call them symptoms of healing) as I went along. Sometimes it was rough, sometimes easier. When I felt I could handle it, I would make a cut and once a cut was made, there was no going back. I made a cut every, oh, maybe 10 days or so. At one point, I had to wait nearly 3 weeks to make a cut.... I was just having a rough time and needed the time to level out again.
I also was very methodical throughout the taper. I pretty much stuck to a 10% cut each time. I kept a journal and documented for myself the symptoms that occurred and anything I did that was progress to me (like a trip to the store, a walk, a phone call to a friend). As the weeks passed, I could see in black and white that I was making progress. Even when I was feeling down and doubtful, I would read that journal and see in black and white that I was indeed progressing.
I guess my advice to you is to keep weaning down slowly and steadily... and to have a solid plan in place for aftercare. Aftercare for me was continuing with a clinical social worker. She actually worked with me during and after the tapers. AA, NA, or private counseling are all good choices... just need to find the one that works for us as individuals.
Hope to hear from you again