It's all fine, don't worry dabbitydibbity.
40 minute naps are normal (in fact the are good, some babies do only 20-30 minutes). Just keep them frequent, exactly as you say you are with your 1h awake time.
Inconsistent awake times (in reference to your other thread) at night is also normal, don't worry too much at this age.
One of your children was easy and the other isn't - also not unusual in families. You may need to try things with DC2 that you didn't need to with DC1 - some children are just more needy in that way. I even know twins who are completely different in terms of sleep, even though they share exactly the same routines.
My only suggestion would be things to make your life easier, rather than seeking to change the already great job you are doing parenting. Such suggestions would start with abandoning "bedtime" for a while. There's just no benefit in it. Your baby won't gain from spending their evening unsettled upstairs, and your relationship with your DH certainly won't benefit.
Just do bath and all that, then bring baby downstairs to continue with the cluster feeding or napping. That way at least you get to sit and watch tv with DH all evening.
I'd also, for the sake of your sanity, keep persevering with the dummy. It allows for comfort sucking so going to sleep without crying.
Feeding more frequently in the daytime, and bigger feeds in the daytime, will mean fewer calories will be needed at night. But this is only of any benefit if you have an alternate way to get baby back to sleep in the night that doesn't involve feeding to sleep (which brings me back to the dummy).