Hi there
Are you giving pain meds before night sleep? Or perhaps at any of the NWs if it has been long enough since the previous pain meds? Teething is horrible, it disturbed my LO for about 12 months!
It looks like you are doing really well with the routine having dropped to 1 nap but perhaps the whole day neds moving on so that WU is later, nap later and BT later - does that sound more suitable to you?
You could do this the way that people move routines when the clocks change, so shifting everything in the day by 15 mins each day for 2 - 4 days until you have a more suitable WU and BT. Do remember during these shifts that meals times need to move too, LOs know where they are in the day based on their meals as much as their nap and bed time. So, day 1 you would need to hold off on morning milk and/or breakfast by 15 mins...keep talking to him and telling him breakfast is coming but it's just delayed. Move snacks, lunch, nap, bath time, everything.
I think a couple of NWs are to be expected if he's teething or during this phase of dropping a nap and shifting the routine. You might get some extra NWs while you shift the routine becaus4e we're talking about a later BT but if he nap was later too then fingers crossed he will manage because the A time before BT shouldn't extend. Lets hope you get just 1 rather than 3.
hope this helps