How to know if my son has mild or severe autism?

Hi everyone. I am new here, last week, my 22-month-old son has been diagnosed autism, the psychologist told us he doesn't know yet if he is asperger, atypical, etc. By now he said  his intelligence seems not affected. How did you knew your kid had mild or severe Autism? I think my son doesn't have many symptoms.  Still I accept the fact he has autism. Here I write a couple of the symptoms my son has at the moment. 

1. He doesn’t answer when we call his name, he doesn’t follow directions, only when i sing a song about putting his shoes on, he knows we are going out so he brings the shoes to me so i can help him to put them on, because he loves being outside.
2. He doesn’t smile back, but when he is really happy he takes my hand or hugs me so we can jump or dance together, he does it with his father too or with his grandma when we are not around.
3. He doesn’t make enough eye contact, sometimes he just looks at strangers and wants to touch their eyes, nose, mouth, like if they were an object, but after he checked the person he just ignore them like they weren’t there. He makes better eye contact with me.
4. When he wants to know the name of some object or letter or number he doesn’t know, he looks at me in the eye showing me the object or pointing at the book he is “reading”, and he waits until he gets a response.
5. He doesn’t point to show me what he likes, or what he finds cool. He just do it to ask for help.
6. He likes to play alone, he was in nursery for 2 months and he would always play alone.
7. He likes letters and numbers, he recognizes many letters of the alphabet and numbers from 1-10. He likes counting every step he takes or every detail from the stuff he plays with.
8. He doesn’t move his hands in a weird way or anything, he moves his head saying know sometimes but very rarely, maybe twice a week.
9. He mimics only the characters of the tv, he hardly does it with us.
10. When we teach him how to play he does it sometimes, for 1 minute and then when he learns how to, he goes away and looks for another toy to play with.
11. He likes playing with my hair, that makes him relax.
12. He used to be very friendly until 15 months old.
13. He says around 20 words btw these words, numbers, alphabet letters, animal sounds, some colors, geometric forms, and he says it only to himself not to show us he knows it, sometimes he hides behind the sofa with his book and “reads” and points the pictures and says the name out loud or just makes words out when he doenst know whats the name of the object.  We are a bilingual family speaking German and Spanish at home . Most of the words he speaks at home is Spanish because I am the one who speaks it, and we are all day together, sometimes he seems to say words in german at night when he is trying to sleep but they don’t make any sense with the context or moment… its like he just repeats what he heard during the day.
14. He doesn’t seem to be sensitive to loud sounds, sometimes he seems not to hear it but some other times he just look+++s at the direction where the sound comes from just to make sure what it is, and then he goes back to his stuff, we were in an airplanes show a couple months ago and he didn’t care about the airplanes loud noises , he loved to see the helicopters. -Extra: when he was born he didn’t cry like the other new-borns in the hospital, he was always quiet, he didn’t eat for 2 days because he fell asleep while eating, he would wake up in the middle of the night, without crying or asking for milk, I catch him once when he was only 1 day old looking at me like analysing me, like if he could see perfectly. I got a bit scared... he didn’t cry when he got vaccinated until he turned 1 year old, he would cry a Little bit and after distracting him he would smile again. He seemed very mature for his age at that time, he slept all night, 12 hours long and ate at morning.
15. He doesn’t walk on his toes, or spins objects or spins himself, he doesn’t line up objects, he just separates sometimes by form or colour, but not always, he likes to put objects inside and out of the toys box. He likes hiding his toys in specific places, like his letters under the sofa and the balls behind the doors, so most of the times we know where he hides things. And he knows it too. He doesn’t-t want everything in a specific order.
16. He likes lights but he doesn’t-t get obsessed with it. He is only obsessed with colors, animal sounds and letters.
17. He dances when he hears music, sometimes try to sing.

Sorry for my bad English, it’s been a long time I don’t speak it or write it, and sorry for the long post. I hope someone could tell me how can I know what kind of autism has my son, or if I should wait a little bit more…

Thanks in advance!