1st question...are you still nursing? I just ask because it seems to me all of the moms I know who are nursing after 1 year of age still have kids that wake in the night.
A lot of women on here recommend the book "The Happiest Kid on the Block" They swear it works wonders.
Personally I am from the Cry it out school of thought. I've used it for 2 kids now starting at 4-5 months and within 3 nights both put themselves to sleep and slept through the night. In my past experience I go in 1 or two times and make sure that there is no real problem. After that my son is on his own. As long as they are not sick or scared, there is no reason why they can't be in their room by themselves and put themselves back to sleep.
Maybe your doctor will have some suggestions..they've heard it all.
But good for you for trying to end it now. One friend has a 2 1/2 year old daughter who JUST started sleeping through the night. Another one has a SIX YEAR OLD who still wakes 5 nights a week and gets into their bed!!