Final straw with 18 month old, ready to sleep train
Hello. My son, almost 18 months, has always been a terrible sleeper. We have kept a consistent bedtime routine since he was 6 months old, and he goes to bed without much fight. The problem is he still wakes 2-6 times a night (or more!), needs to be rocked/held/and nursed. We have tried a sleep consultant 4 times between 7 and 12 months without much success. Twice I have gotten desperate and let him CIO. The first time was about 3 months ago and he fell asleep after 45 minutes, but woke up 12 minutes later and spent another 40 minutes crying before falling asleep and then again woke up after about 10 minutes, so I went and settled him to sleep by rocking him. The 2nd time was last night after being up with him from 10:20pm (he went down at 8:25) until 1am which is when I set him in his crib and walked out. He cried for 80 minutes before I ended up going in and settling him.
His days/sleep schedule are:
Wakeup 6-6:15 am on his own, nap around 10:30/11 for 1.5-2 hours (so wakeup around 12-1) and then we do an evening walk at 6:15, bath at 7, brush teeth, pajamas, books, classical music while we say goodnight to the house (this part was recommended by sleep consultant), then sleep sack and rock to sleep by 8. He goes down for nap and bedtime without really any fuss or fight. It's the constant wakings that are difficult and I am ready to do whatever it takes to get him to stop.
I have read a lot of conflicting things about sleep training methods at this age. Some say to go full extinction because check-ins at this age cause too much stimulation/upset and others say to do the chair method which contradicts the 'too much stimulation' theory. I already know I need to stop the comfort nursing...but please walk me through the appropriate method to build his self-soothing skills so he can fall asleep without so much assistance. I am literally on the verge of a mental breakdown and cannot continue my nights like this.