K.D.
My DD didn't really co-sleep, but she did know I would bring her to bed with me most nights if she was super fussy. DH wanted our bed back and I was done nursing about the same time that you are at now. I have not read "The Baby Whisperer", but "The No Cry Sleep Solution" has some of the same techniques you mention. However, instead of just wordlessly laying him back down from the start, lay him down and rub his back. Try a 'sleep cue' noise or word with him. Put the shirt you wore yesterday in bed with him, so he can smell you there. Any change in the sleep routine is going to demand time from you. At the start, it may be hours of your day teaching him this new way to sleep, but focus on your goals and know that it WILL get better. At 21 months my DD still wakes about 1 time per night, I just go lay her back down and she's back to sleep in about 30 secs-2 mins most of the time.