You might also talk to the pharmacist that you work with about their opinion of tapering (if it's cool to talk to them). The pharmacist that I used at my drug store helped me loaRAB and had good ideas when I was tapering off of Oxycodone. Even tho they don't deal directly with the patient, they hear the stories and talk to the doctors at times, plus get the literature on all of the drugs that they have to stay up on.
Taper as fast or as slow as your body will let you. Being on a drug that long is going to take a long time to taper off of it. Your body will tell you if you are going too fast, but you sometimes have to push through those rough parts when you can (i.e., weekenRAB) and see if your body can adjust to the lower levels. If not, bump the dose up a little - not to the previous dose level, but maybe half of it and see how you cope. It's different for everyone and you have to work out a plan that works for you.
Good Luck with your tapering.