I think you should be absolutely wrapped for lasting two years! I am not an addict, but I grew up with addicts all around me, addiction runs on both sides of my family. My mother lasted 3 months when she came out of rehab, and 5 hours after she she got out of detox, before she relapsed.
Sadly it's something you have to keep fighting, no matter how long it's been. While my mother was in rehab, and after she got out, I was doing some group therapy to deal with things, and one thing I remember being told is that there is apparently a pattern of when people seem to relapse most often and nobody really knows why. Don't quote me on it but I think one of those points was at 2 years. I wish I'd written it down.

Has anyone else heard of that? If I am correct in my facts (and again, don't quote me on this because I could be wrong), then it might explain why you are suddenly craving again after 2 years.