Help! Am I ready to sleep train?

I have a four month old LO and sleep has become such a problem. I want to sleep train but also want to make sure we’re in the right place with the right schedule and choose the right method first.

He was getting 5-8 hr stretches before sleep regression. He was also going down independently in his bassinet (snoo). We were borrowing the snoo and the original owners asked for it back and so we figured it was about time to transition to crib anyhow. However we also dropped the swaddle at the same time and needed to adjust his bedtime because he was sleeping at 9pm and he started screaming around 6-7pm, indicating he needed an earlier bedtime. So lots of change for LO.

So now we’re doing ~3 naps a day tho sometimes we need a rescue nap at the end. He wakes up between 6:40 and 7 and then does something like a 1.25/1.75/2/2.25 schedule for 3 naps. Naps usually last 1-1.5 hrs and sometimes he wakes up screaming and sometimes happy. Most naps are contact/carrier naps or in a pram with an occasional crib nap. I’ve been shortening wws as he has been overtired and was having false starts that corrected with shorter wws. Bedtime is generally 6-7ish but varies.

He sleeps in a crib in our room right next to me (I can reach in and touch him). Bedtime routine is bath (some days), breastfeed, massage, book, song. He is generally screaming within a couple mins of being placed in crib and then needs to be rocked or fed to calm down. Sometimes we can put him in there after being rocked or fed and then shush pat to sleep but it’s rare. He then wakes up every two hours absolutely screaming. He has intense feed to sleep association so he will continue to scream if picked up and rocked for about 20 minutes before calming. If fed, he will calm down. I remove him if he is just suckling without getting milk but then he will scream inconsolably if he isn’t passed out. After that, it will take 10-20 minutes of holding and rocking to calm him. If he’s placed in crib awake after the feed, he will usually scream bloody murder and then it’s either back to the boob or another long period to calm him. We try to eventually shush pat him to sleep in crib but it’s not every time.

We try shush patting him in crib at every wake but it rarely works and he generally screams inconsolably. We try a pacifier everyday but he isn’t taking it.

He is currently EBF. He has recently been having more green watery poops and we don’t know why. He also has some bad gas and always has. I’ve been feeding at every wake because I’m nervous that something is off with digestion because of green poops.

The situation and the screaming is untenable longterm and I’m sometimes getting to a point where I’m so fed up with the sleep deprivation and screaming that I am losing empathy. I want to sleep train but am worried about whether he’s ready, if our schedule is ok, whether I need to wait until his poop situation normalizes, and what method to use. The intense screaming feels like it could lend itself to some horrible sleep training experiences. Any thoughts or advice would be helpful.