How do you know if your son autism

Chrissy • I love my family and proud mother of four beautiful boys and taken by my soulmate !
My son is now five but before I seen the signs cause I checked and seen some in him and took him to the doctor and they tell me something totally different so I'm lost his dad other kids have to but savvier and I think he had it to and need to get the help I need for him cause I don't want him to be made fun of or thinking he's bad when he starts school in August I've been trying to tAke it one step at a time he's special and I would have any other way just need help any advice please