Hi Hun,
First of all (HUGS) it's really hard when you don't know what to do first. Especially when illness has been at play. Here is what I would do Hun.
First of all address the OT issue, because tweaking routine is very hard starting out from an OT standpoint. Our DS didn't respond to WI/WO until he was 3, it would have the same affect as you described, so Gradual Withdrawal always worked better for him. I have BTDT with the bottle when DS was 11 months old and going through awful teething! I would definitely cut the bottle altogether as of now. Leave a sippy with water in his cot, so you can rule out him being thirsty (if you're a worrier like me this may cross your mind
)
It's great he is going to sleep by himself again, so well done on that. But it is possible that he is waking in the night instead of resettling because he thinks "Hmm I'll say hello to Mammy and have a little bit milk now" KWIM
IIWM for the NW I would start GW. Go into him, use your sleepy phrase only ie: "Sleepy time Darling" and then it's up to you to decide where you would like to start the process ie: sitting by the cot (not looking at him) until he lies himself down, or sit further away at a starting point, you're the one to judge that. Do that for all NW. The other alternative is to try 'Wake to sleep' if his wake up's are consistently at the same time, let me know if you need more info on that (Can't find the link
)
The EW are unlikely to go until he has caught up on some sleep. I doubt that it is routine related right now TBH, but time will tell.
TBH with you, even though he is EW, IME with DS it is helpful to shorten the A time to nap after illness, but that sounds tricky with daycare. So in the first instance I would stick with what you have and deal with the NW.
How does that sound
Oh if I had a pound for every time I thought I'd cocked things up permanently
you haven't Hun, these things happen and it won't be the last time, but once a LO is an independent sleeper you can always get back there, with patience and support which you have.
Let me know your thoughts, you know him best.
Love Vicki.x.