So teething will definitely cause havoc at nighttime as you know. Just try and medicate with ibuprofen as often as you can (every 6hrs I think) for the time being. But I do think it shouldn't be causing too much of an issue going down at BT per se. Especially of you can medicate beforehand.
I'm actually wondering if he's UT at BT yk? After a decent nap of 1.5hrs I would say definitely that a BT 3hrs later is just not enough for him. You've got room to lengthen your day a bit more too. It is very usual to have 13hr days through transitions and you're trying for a 12hr one really with actually quite a bit of day sleep for a 13mo. Not unheard of, but I do wonder if we should push BT back a bit. Wdyt?
As he feel asleep yesterday at 8.10pm, I'm thinking perhaps try a 12.5hr day for now and shoot for BT 3.5hrs after the afternoon nap has ended for now? I do think it'll have to be moved later or modify the routine elsewhere, but it's a good place to start.
Fwiw at 13mo my DD and many, many others are over the 5hrs A mark before nap and BT. 3hrs A is actually very close to what a 6mo would be doing so maybe unrealistic to ask him to go to bed so early? Xx.
Average A times- BOOKMARK ME! Eta have you introduced a lovey or something? That really does tend to help during SA and any other times actually. Is there a particular stuffed animal he likes? Or maybe a muslin (these are great as you can wash and swop them around).
P.s I'm going to move this over to toddler sleep as he's 13mo, but I will keep with it as a mod ok? Just want it in the right place x