My DD 3.5yrs probably has ASD (pending assessment!) and she didn't score much on the m-chat. She's globally delayed also. This is just my experience/story which might help...
She looks at things we point at, she does pretend play and has done since young like feeding her dolly etc (although it would be considered very limited for the age she is at now, less obvious when younger), points, waves, claps, smiles at us, makes eye contact, is interested in other children (although again for age now this is limited, again more obvious now she's 3.5), not particularly bothered by noise, understands simple instructions, eats well, sleeps well, no issues with clothes (she absolutely loves choosing different outfits and accessories!!), no classic/obvious stims like hand flapping/spinning/finger wiggling, loves books and very engaged in the stories.
She does however often ignore her name, her stim from young was rubbing behind her ears which is much less obvious, walked very late but this was actually due to hypermobility, doesn't understand other's emotion, put her fingers in her ears, rigidly organises and lines things up and likes things a certain way, obsessively interested in things like drains, struggles with transitions like tidy up time at toddler groups, delayed speech and language (knows numbers, letters, colours, animals etc but very little functional conversation speech), reverses pronouns, echolalia, pica, can be very much in her own bubble although she interacts a lot with us too.
Going to mainstream pre-school has really helped, so this might be worth trying a couple of mornings a week? Speech delay definitely can be just that though. I found looking at a few different more in depth lists of autism symptoms helpful in identifying that my dd actually does tick many of the boxes.