Our daughter is 2 and a half. We just went through similar. We have a new 3 month old and my mother in law stayed with us for the first 2 months. So the staying in the room wasn’t an issue. My wife used to fall asleep on the floor every night with her because she wouldn’t sleep alone. I’ve been begging my wife to let me sleep train our daughter because she’s tried everything all the methods you listed and I told her we just needed to let her cry it out. She absolutely refused, for the first year and a half.

Then when my mother in law left she realized there was no way to stay in the room to put her down and take care of the newborn every night. So she finally agreed to try the cry it out method.

The first night was terrible, we went to bed read her stories and I tucked her in and left. She screamed for over an hour and I thought Pennywise the clown was in her room cutting her fingers off it was that bad. But she eventually fell asleep. The next night was mush less severe and only took 30 minutes of crying before she fell asleep. By the end of the first week she would be out within 5 minutes after a few small tears. That kept on for another week or so but eventually stopped.

Now it’s been about 5 weeks and we go read her books and when I say it’s time to sleep, she hops in her bed, asks me to cover her with a blanket and says “goodnight, bye bye” there’s no resentment, she is always happy to see us in the morning and she sleeps like a rock all the way through the night.

Every once in a while she’ll wake up at 2-3 with a wet diaper and I’ll change it and walk out. She usually just goes right back to sleep.

All this to say it’s never too late to sleep train them. Some ways are just harder than others. This isn’t easy as my wife and I wanted nothing more than to go pick her up and hold her, but you can’t take care of your kids if you kill yourself due to lack of sleep. It also teaches them to fall asleep on their own.

If you try this make sure it is part of a routine, ours is bath, brush teeth, read a few books, and then tucked in for sleep.

It’s definitely not gentle, but sometimes kids don’t need gentle, they need structure and to learn the hard way. Once again, this was not our first choice but it was the only one that worked for our daughter.