8.5 month old naps - any advice 😳

I will try to make this as short as possible but any advice would be so kindly received!!!

Ever since my baby was a minute old he has only ever catnapped, he has never napped more than 45 minutes in the daytime. Now I was told that this should all start changing around 4/5 months old and he would naturally extend his naps. We are now 8.5 months old and it’s EXACTLY the same - except probably worse because he will only have two of these very short naps a day instead of the 4/5 we used to do 😂

Now to point out he goes to sleep at around 6.30pm every night and generally sleeps till 4.30am, has a bottle and goes back to sleep till 6am(ish). I’ve tried giving him his first nap after all different wake times (2 hours/3hours) nothing changes his naps. He also will NOT put himself to sleep in the day..but does at night? He just screams and I can’t leave him like that so I give him a cuddle and put him back in his cot - where he will stay for 30 mins or so!

I have TWO blackout blinds, it’s a cool room, it’s quiet and he always has a nicely filled belly before nap time (including offering of milk!).

I know these naps aren’t enough for him as he wakes up very upset and will almost always fall back to sleep when I get him out the cot.

So why won’t he go to sleep himself in the day time? But will at night?

I’ve tried literally everything that anyone has suggested even as newborn we tried swaddling etc. I’ve tried a mini bedtime routine - literally NOTHING works. Even if we’re out for the day & he falls asleep in the car or pram it is still ONLY for 30/45 minutes.

Any tips? Or should I just hang fire till he drops to one nap? And keep going with the 30 minutes? I make him wait for his next nap if he gets up early.

I worry as he is going to nursery at 12 months and I know they won’t put him to sleep how I do and I cannot think he is laying there crying 😭