Hi there, at this age my DS was starting to have a few NND but if he did nap we capped it at 1.5 hours with a 13 hour day, NND max 11.5/12 hour day (we have an EW so 11 hours is impossible)
If you want an earlier BT I'd say try capping it at 1.5 hours if you've been giving 2 hours and moving BT 15 mins earlier and see how that works for a week. So WU 7/7.30 nap 1.5 and BT 8/8.30?
Do u think he may be OT with all the later BT and NW? With regards to sitting in the chair, I'd tell him before BT that you will have stories and cuddles but then you will be leaving the room as you have to get ready for bed, tell him that you are just outside his room and keep popping in if he shouts for you or cries. Does he have a lovely or bed toy? We used to make a big deal of tucking all bed friends in too and choosing who was sleeping where on the pillow, all this made him feel more chilled in bed.
We had a phase of sitting on the stairs just saying night night mummy's here on the step sleep well.
I'm sure if he was an independent sleeper it will come back soon hun, do you talk about new baby or has he not really cottoned on? xx