We did 'sleep training round 2' at 3 - sitting in chair in his room, gradually moving toward door over 2 weeks.

This is so normal. Toddlers don't have an internal drive to sleep alone.

Reward chart for staying in own bed worked at 3.5 for us. Wouldn't have worked earlier.

Floor bed mattress on the floor in his room. He could come find us but had his own cozy space too.

Cultural - co-sleeping is the global norm. Don't beat yourself up.