every baby at their own pace ?

my son is 17 months , & it’s just us at the house . he hasn’t been around any other babies ever really . and it’s always for a quick second if we do . i don’t have very much close family or friends so would that be a reason he isn’t walking ? he is healthy and strong and will stand in the walker and go backwards but not forward . i feel like maybe he can he just doesn’t ? he is also so small compared to other babies . ( i’m 4’10) though . i just see other kids and start to worry .