Hey, ladies.
First, DM, (((((((hugs))))))). All that sickness is not good! Sending well wishes, and I hope that your DS gets better soon, and that you get a break, too. You can always go back to sleep training once this is all sorted through!
Grants, your DS is just a little older than mine, so I can only compare my lo and yours, and from the look of things, I don't think you have to be too concerned with the fact that he is getting less sleep in general. My lo is doing about 12 hours total sleep right now, with 10 hours nightsleep and 2 hours (avg) total on naps. (Although the other day he gave me that 3 hour nap, which I normally wouldn't let him do, except that I didn't know how long to let him sleep as he has never done just 1 nap before.) Anyway, I also looked at my sleep diary for both DS and DD. They are similar, although I have to say that my los are "not typical" with BW recommended amounts of sleep. I always seem to come up short, but no matter what I do, I have never been able to extend sleep amounts. Having said that, when they were babies, they were doing 15 hours total sleep, and by 1 year, DD was doing about 12 hours total sleep, and it looks like now DS is following pretty much the same pattern.
So, looking at your routine, it looks like your DS is doing a similar routine to mine about a month ago. So it could be that your lo might be getting too much sleep, maybe?? Some kids just can handle less sleep. Is he tired by bedtime or not? I know it sounds late, but my DS has been getting to bed around 8:00 pm, and waking at 6:00 AM. Even that weird 3 hour nap didn't mess up his BT. If your lo is tired by bedtime, but he is getting up around 5:00 or 5:30 consistently, have you thought of trying w2s around 4:45? Your 4:30 "happy" EW, IMHO, sounds like he needs longer days. . .but, I'm only making that guess based on what my own DS is doing and has nothing to do with BW...
Today, I had another day with only 1 nap, and I'm TOTALLY surprised that DS lasted all the way until 13:45 before his nap, then he only took a 1.5 hour nap and was completely fine all the way until BT at 20:00. He did get fussy around his morning nap time, which used to be around 10:30 AM, but we've been taking swim lessons which start at 10:40, so I think he gets a second wind from the cold water during swim class. And after that, I keep thinking he's going to be so tired after swimming, etc., but he just keeps going. So, I might have been forced to transition to 1 nap! And if DS sttn again, perhaps that's all the sleep he needs, afterall. Cross fingers.
But, on the independent sleep, front, I have been posting on the props board about bouncing and rocking as props, and they suggested to let lo play in cot for wind-down (which mine happily does) and wo. If he cries (real cry, that is, not that mantra cry), then wi and start doing pd to settle. I guess I am not supposed to do pd when he's happy, otherwise it becomes a push down/stand up game. Anyway, I did that for nap today, and it worked like a charm. He played in his crib for about 20 minutes, started to cry, I came in to settle, and pd only 1 time, and he fell asleep.