3.5 year old still not potty trained?

Im at my wits end ladies 😩 Ive been try to potty train my son for awhile now and though he understands the concept, he still has frequent accidents. At home, he has no pullups on, bare bum. And sometimes does tell me he needs the potty. Daycare wont take him out of pullups yet since they say while he does pee in the potty when they all use the washroom, he still hasnt learned to TELL THE TEACHER he has to go😅

Ive trie everything to teach him. I think the inconsistency between being in pullups at school and none at home confuses him but they just wont budge as they dont wanna deal with accidents. Ive spent long weekends trying and trying to teach him.

He has always learned things later than his peers. Walked late talked late etc so I know he will get it eventually. But he starts kindergarten at age 4 here and should be fully trained, so Im getting super nervous! Im a single mom as well so i dont have much help here.