I am so glad you feel you are getting somewhere - I know what a relief it is just to see a bit of a positive change and start hoping there is light at the end if the tunnel!
I think at 9 months one longer & one shorter nap is quite common as babies head towards the 2-1 nap transition, so your nap duration doesn't surprise me, but the fact he is fighting number 2 means there is probably some more tweaking to do.
When you say you LO does 12-12.5 nights is that STTN or are you classing his NWs in there too?
Your last A is incredibly short - is he easy to get to bed & does he stay asleep? If he is waking lots, I think you might have an UT baby & that can be fixed with routine changes.
My LO only ever sleeps 10-10.5 hours a night (not inc NWs) so we have very long days and a late bedtime (otherwise he'd start his day at 4am
) so to me your day looks on the short side - but if you LO is doing fantastic 12.5hr nights straight through, then obviously I'd say don't fix what ain't broken!!