Hi there and welcome to the forums
It's great to read your story and to hear that the past threads have helped you so much
It could well be the regression come early, the good news about that is that it will be over early too!
However, it may not be the 18 month regression but something else, in which case you have this to go through and then the 18 month regression too.
The thing to remember is that ALL these things are phases. When you think you are at the end of your tether take a very, very deep breath and remind yourself that this will pass. My DS was self settling from around 8 wks old but guess what, I still had ALL the developmental phases, the regressions, the routine changes, nap drops, teething and everything else which disturbs them to go through, just like anyone else. There were certainly times I felt at a loss.
Developmental leaps such as walking and running often bring sleep disturbances and bouts of SA 9seperataion anxiety), the increased ability to get around means they can get themselves into more danger so it is really quite clever that at the same time they suddenly feel they need to be with Mummy every second of the day (and night) to check that they are okay and safe.
Mostly with any of these phases (teething and developments) you will need to put in extra time, as you have been doing, sometimes you may need a routine change as you have been trying.
As nap times have been dragging out with his refusals I'd probably just start the WD much later (avoiding an hour of that refusal) and then when you do take him to nap be willing and prepared to give him what he needs in terms of additional help, a song, or cuddle, even staying with him until he is asleep for a few days if this helps to keep him relaxed rather than running around. Getting the sleep habit back in place, nice and relaxed, before trying to remove yourself, could well help.
In terms of routine, he might actually need a much longer first A time but possibly not a later BT, sometimes the nap just needs to be later in the day. This means you might keep the nap an hour later than your current routine. It could be though that once he is settling down calmly again he won't need it so late so you can be ready to bring it a bit earlier (in increments) once this phase of refusal is over. I have done this with my DS with his BT when he was refusing for an hour, I just move BT an hour later to avoid the struggles (then helped a lot, songs etc and verbal reassurance from outside the room or stayed with him until fully asleep if needed) and then when I saw the phase was ending I moved BT 15 min earlier, then another 15 mins earlier etc until he was back to his normal BT. This is because he still needed all that sleep even though he was refusing it.
I would probably also help him transition if he is short napping. If he falls asleep without you there go in again before he wakes and help to sooth him to keep him relaxed throughout the nap. If he needs you there to fall asleep you might be able to pop out for a few mins before going back in to help again.
Try not to worry about how much you help him, the main thing is to maintain the trust and keep your bond strong. Everything else can be fixed with WIWO and/or verbal reassurance or gentle weaning. Plus, most LOs who can self settle will return to self settling just as soon as they can with little or no encouragement to do so.
One other thing I wanted to add is that you can talk about things with your LO when it is not sleep time. Tell him how nap time will be, that you will help him, tell him he needs his rest and sleep so that he has energy to play well, tell him you will always come when he needs you. These things are very reassuring and often LOs surprise us with how much they seem to take in which we wouldn't expect them to understand.
I hope this helps some
