you can also try keeping your shirt or any other clothing with your scent with him while you are making him sleep alone. Your smell from clothes will help him sleep bit more comfortably in the start. This helped my pup.. but still if finds way in our room want to sleep with us :) .
without AKC papers or DNA test you cannot be 100% sure... but after 1 year you can compare it to breed standards ... that wud give a general idea... and until n unless you are thinking of breeding or a breeder ... you shouldn't be worried about ... only thing you can worry about is ... health issues with parents if any ... pure or mix all they give or demand is just love ..