Looks like your routine is pretty good. I'm thinking that an ideal A time for him seems to be from about 1 hr 30 - 1 hr 45 min in the morning, and then he handles about 2 hr pretty well after that. I'm looking at the time from when he first wakes until he goes to sleep (the E is actually included in A time). It is definitely difficult when they short nap that last nap, but quite common at this age, because if he's getting two full naps in early in the day, that last one often ends up as a CN.
S - 16:45 - 17:13 (here he woke up. My guess - he suffered from gas, since he woke up a bit crying and I couldn't make him back to sleep. From here things got worse...)
A - 17:20 - 18:00
E - 18:00 - 18:20
A - 18:20 - 19:30
S - 19:30 -
Then I fed him (like a DF) at 20:30 and also tried at 23:30 to give a pumped milk - but he ate only 30ml (1 oz).
What I would have done here is to feed him upon waking, say 17:30ish and then again at about 18:45ish (could be just a top due to the 17:30 feed) and put him to bed at 19:00. This way, he gets a couple cluster feeds to get more into him and an early bedtime due to that short nap. Then, I'd wait and do the DF at 22:30 and just do the one. My guess is that he didn't take much at the 23:30 feed, because he'd already had somewhat of a cluster feed at 18:00 and 20:30, so wasn't super hungry and was also probably in a deeper sleep.
S - 17:25 - 18:00 - and here again he woke up and seemed like tummy aces. This time I didn't fed him as I felt he's more tired and upset than hungry.
A - (part of it was crying :-( ) - 18:00 - 19:30 - this included in the end the BT
E - 19:30 - 20:00
This time I actually think the A time before the nap was a bit too long, it was over 2 hr since he last woke at 15:15. So, I think it was an OT nap. Again, I would have fed him upon waking (after you soothed him a bit: rubbed his tummy/back, did a few bicycles with his legs, walked around, etc), so at about 18:15. Then, I'd do the cluster feed at 19:15 and aim to have him in bed at 19:30, with a DF between 22:30 and 23:00.
I think there's a good chance he's not taking much at the DF from the bottle because it's too late and he's in a deeper part of sleep, or he may just not prefer the bottle at that time.
The DF doesn't seem to work for all babies, so if it's more of a hassle to try to get him to take it, you might try just letting him sleep and feeding him when he wakes. The two NFs he's got right now are totally normal for his age.
I feel the evening routine is still confused since I don't know what to do when he wakes up after 40 min from the catnap. It's hard since there are two other sisters and this is the evening dinner and bath for them also....
What should I do?
It's definitely hard to work everything out in the evening for everyone, I understand that. After a short CN, I guess I'd try to get him in bed earlier if possible and then you can concentrate on bath and such with his sisters. Would that work?