Congratulations on 20 months thats something to celebrate.

As far as will the urges ever stop, well that's different for everyone. I went 10 years without cutting then about 6 months ago relapsed. During those 10 years there were periods that I hardly ever thought about it, then I would go through weeks and even months were it was all I could think about. I would have my wife lock everything away so that I couldn't then work down the list of alternatives to SI that I found on this site. Its important however if you do relapse to accept it and jump back up on the wagon again.

At the worst times I found going to AA helped, SI seems remarkably similar to alcoholism and no one but my sponsor knew that I was there for SI and not drinking.