Might take a little bit of trial an error on BT. Many people aim for a 10 hr day allowing a 14 hr night, the night can go as long as this as the NNDs build up and he becomes more and more tired across the week/s. That said, mine was doing roughly 12hrs total sleep in 24hrs and when the nap went he did 12hr nights. Looking back over the thread it seems he was doing 13hrs total sleep in 24 hrs but that this has dropped to 11.5hrs would you agree? I think I'd aim for 12hr day and 12hr night but record his sleep times and mood so you can see how he's doing on it. He might need a longer night. What do you think?
It's also great news that he appears to tack on in the morning hours and WU later if he needs more sleep so you can judge BT from there. He might also be finding it hard to adapt to the changes that are going on, BBB, and you expecting number 2, I doubt you have the energy but perhaps a few more cuddles are needed to reassure him. Maybe nap can be replaced with quiet time cuddling on the sofa with you? Don't know how you feel about TV but it kind of saves us when DS needs to zone out and chill, it really seems to give him a break.
Some people also find that they can drop to say 1 nap per week or 1 every two weeks, don't feel that you can never ever go back to a nap if he looks like he really needs it yk. In the first couple of weeks after mine stopped napping I invited him once to go sleep in my bed with me for a nap after lunch, I was amazed he said yes, this had never happened before, we both slept 2hrs! Hasn't happening since but it did help after a couple of weeks of no nap.
How's that sound?