Ok, at 5 months, average A time is around 2:15 to 2:30 or thereabouts - 2:45-3hr at 6 months.
If he's dozing til 9am, what time is bedtime?
I think if you want to get a more steady daytime routine, I'd get him up at 6:30 when he wakes and just start the day there with a nap at 8:45 or 9. You could do a topup feed at 7:30 then feed after the nap if you're looking to get your feeds more consolidated and stop feeding to sleep. The 45min nap means he's UT for that first nap and no surprise given he's having an A time appropriate for a 3 month old.
The day might look a bit like this:
6:30 - WU, E
7:30 - offer topup E
9 - nap
10:30 - WU, E
11:30 - offer topup E
1 - nap
2:30 - WU, E
3:30 - offer topup E
5 - catnap 45 min
5:45 - cluster feed if you/LO wish
6:30 - BT routine - bath, feed, bed aiming for sleep by 7/7:30
As he gets used to going that amount of time between feeds, you can gradually move the topup feeds closer to the main feeds and consolidate them so you're feeding on WU. You may find they persist until you establish solids though.