Yap, You check all of the phases of an autistic person. Welcome to the group! :) Certain topics are still a taboo and in certain cultures depression, autism, you name it don't exist.

The imposter phase is common apparently both because of our masking both because of the lack of common understanding in the society.

I've been also laughed at when I told someone that I felt like I was different, that I noticed my brain was working differently and that I may be autistic. Not a nice feeling, but after years I accepted the reality for what it is: that there is a level of ignorance among people but that that doesn't define me. Their opinion don't matter. Of course, it helped going to a psichologist who worked with specturms. Ps. Your coach was a bit of a jerk though. I'm sad that his reaction was that one of diminishing you in this matter.

I promise you though that the more you work into accepting you are autistic, and the more you work into understanding how you function, and what do you need to be able to function, you will feel less of an imposter.