SUPER WORRIED , SHOULD HE BE TESTED?

so my son was born around the same time as this other girls child ik, i believe about a week apart hers was a few days early and mine was a week over due...so ik he was well done, but now her baby is a year old and walking and talking and has teeth but my baby does not do or have any of those things, he has the same behavior and motor skill as a 9-11month old.

i find it worrying and frustrating bc the girl is one of those mothers that are on thier phone all day or out with guys or doing everything and anything but watching her kids but me being a ftm im all over everything the books say and helping and aiding him in all kinds of exercises but idk why he isnt showing any signs of advancement........is this normal???? help please