One thing I’ve wondered is if his awake times should be longer and that the short naps aren’t the result of him being undertired but I strongly suspect they’re the result of being overtired... help!!!
Well, your wondering is correct and second guessing yourself is not ideal
He's probably got some chronic overtiredness running in the background from not sleeping well for a long time. He doesn't need to pay back that sleep debt minute for minute. He needs to get good restorative sleep by having A times that are long enough for him to take good long naps.
Average A time at this age is 2:15, so he will likely be UT with only 1:45-2hr.
Doing PUPD as long as you are burns a LOT of calories and will start to affect your sanity. Do you think you have a feel for whether he will go back to sleep within 10-15mins of starting? If so, I'd go for 10-15mins and keep going if he's close to going back to sleep but just stop and get on with the next cycle of EAS if he's not going back to sleep because otherwise you will get to a point of him being very OT from PUPD counting as sleep time.
up until now we have been feeding on demand so he can’t go 4 hours without eating during the day but we are working on reducing the number of feedings so that he’s more efficient at each one.
That's great. Plenty of EBF babies cannot go 4hr between feeds until solids are better established. For this reason, I have found myself suggesting a topup feed an hour after the main wakeup feed which you'd then replace with solids when you do start them.
We’re also not too concerned about cutting out night feedings at this stage
Also very sensible. NFs usually self-rationalise so long as there's not a feed to sleep prop going. Plenty of babies this age still need multiple NFs too.
My suggestion is to keep following the principles of the plan with a routine a little more like this:
7 - wake, feed
8 - topup feed
9:15 - nap
10:45 - wake, feed
11:45 - topup feed
1pm - nap
2:30 - wake, feed
3:30 - topup feed
4:45 - nap
5:30 - wake, feed
BT routine incl. feed
7:30 - asleep for the night
I would also say that PUPD is a method of last resort for use if shush/pat has been used consistently for at least 2 weeks with no improvement. You can certainly use shush/pat or some variant that works for you and your baby (the basic idea is that there's a sound for him to listen to and touch for him to feel). You may find with increasing A times that much, he may wake 30mins into his nap - OT waking which is usually easily resettled if you're there before he gets really upset and use the same soothing method as you used for going to sleep.