Should I get a second opinion?

Hi, 

I've already posted here recently but it was before I had my feedback interview so I have sort of an update on my situation. 

I recently received a result saying I didn't meet the criteria what I was initially understanding of. Today I asked this assessor who did my ADOS test why he thinks I scored low points. He said that because I could look at him for even a second when he was talking to me that anyone who is autistic wouldn't even acknowledge him. He also said that a sign was that he told me a joke and I laughed and that anyone who is autistic does not show any facial expressions. I told him that my special interest was video games at this assessment as I not only spend basically all my time playing games to the point I neglect important things, when I'm not playing games I'm watching video analysis of game design and looking up videogame trivia, he said that videogames aren't a special interest and they're just something that people get addicted to. He also said that if I was autistic my behaviour wouldn't change regardless of my surroundings so I would behave around my parents the exact same way I would around complete strangers who are making me anxious. 

At this point I sort of just felt like this assessment wasn't at all based on any kind of any ASD spectrum and just came down to that if you didn't show the stereotypical traits of someone who is low functioning then you're not autistic at all.

I know these are professionals and I'm not but I just personally feel like this particular assessor was basically using no intuition and just basing his decision off stringent guidelines made to only diagnose people who can't even function in everyday life.

I was just wondering what everyones thoughts on this were and if I should seek some kind of private diagnosis as I asked this assessor for an appeal and he said he wouldn't know who to go to and I'll have to return to my GP and start this whole 3 year process again.

Thank you if you read this.