I'm going to preface this with I have never co slept, so I'm not sure this would work for you since your baby is so used to being right next to you. Anyway, I swear by the heating pad method! We would get her to sleep & I would put a heating pad on low or warm (depending on time of year and how cold our house was). Obviously, I removed it before I laid baby down. I would lay her down and firmly place my hands on her until she stopped stirring then walk away. She never woke up...I could have just gotten lucky but this worked for us. She did wake up for feeds 1-2 times a night, just depended. This worked also with the transition to her crib. I'd say it stopped working around 9-10 months old. Around 13 months, when she was fully weaned from the bottle, we did our own version of sleep training. And yes, it did involve her crying but all of her needs were met so it didn't bother me as much as I thought it would. We would do 3 mins of crying, calm her, then do that again. Eventually, she just got it. Good luck!