I've not flown on one yet. Hopefully won't... but yes, I had a look and you're right it does have a bulkhead, probably to increase galley space. Very interesting they got 189 seats in and put a bulkhead! I bet the galley situation is terrible...
I'd have thought they'd want to make them Y186 like the rest of the fleet.
By the way your 175 seats don't match anything, 175 is 1AB/CD.
Flights can be changed on the day, so this whole discussion could be pointless and you end up on a LO MAX or just a 738.