Wits end! 9m overtired or under?

Hi,

our 9 month old was sleep trained at 8m by Ferber and did pretty well initially but since dropping to 2 naps about 10 days ago things have gone downhill. Hes pretty consistently waking at 10pm, 2pm and 4pm and we often then have to co sleep 5-6 to get him to lie in. He’s on 3/3.75/2.75. Usually up at 6am and putting down at 6pm. I know we probably need to shift bedtime later but tried and he’d just wake earlier - what with dropping nap weve assumed overtired and done 6pm bed to try and help but no luck

he’s started crawling AND cruising in the last week.
EBF. Have been offering x2 night feeds.
goes down independently.

lots of sep anxiety at the moment.

any thoughts much appreciated.