You are very welcome - I'm glad to hear that things are somewhat easier for you.
For a consistent routine you can kind of just force it, I mean, so long as the A times are basically appropriate for age and the E times are basically appropriate for age/hunger then you can work with these to implement a routine which best fits what you need to do in the day.
For example, my DS when he was a baby I could alter his first A time as he needed based on his development, he needed a long first A time and did a consistent 2hr nap in his cot for the first nap of the day. After that though I had a fixed time twice per week where I absolutely had to be at an appointment on time so I "forced" the rest of the day in the best way I could, being as respectful to my DS as possible whilst also meeting this unavoidable need. The way I worked it was a car nap on the way to the appointment and another on the way home. I timed leaving the house so that he could fall asleep in the car, this sometimes meant leaving earlier than I wanted but it helped him get a nap on time, I could let him finish his cycle in the car before the appointment. There were times he would have slept longer than one cycle but I had to wake him, yes he was not happy, he had to do a full, long A time and then would be back in the car for third nap which was basically a set nap time rather than based on A times. It's not ideal, it's not perfect but he got used to it. He got so used to it that even on the days I did not have that appointment I had to car-nap him as he was so much in the habit of sleeping in the car, if I tried to put him in the cot for second nap I got refusal even though he was perfectly happy to do so for first nap.
I think you could do something similar with your routine, you can look at when/where you need to go out and see what fits with baby and also encourage baby to fit with the rest of the family, it's a bit of a compromise all round but that's family life isn't it?
If morning WU time being different every day is throwing your routine off you could wake him at a set time, he will likely pick up the habit and start waking at that time or gradually become less of a grouch over it. Naps can be "set" but set based on as close as you can to his ideal A time is better.
Does this help you think about your own routine perhaps?
Our LO has slept for a couple of cycles without resettling a few times but usually still needs resettling after 30-40 mins. Interestingly he often then goes for 2 more cycles without more resettling and I think this must mean OT rather than UT
On this, I'm not convinced it means OT but can't say anything for certain. he could just be learning to sleep longer naps. 4-6 months is prime time for short naps and needing to help LO resettle or accept short naps so to be honest you are doing brilliantly to get a longer nap even if you do need to resettle once, and LO is doing great to get 3 sleep cycles, it's really good compared to many routines at this age.