It's sad that you feel you've been pushed out of autism advocacy because more vocal people who may not be autistic but think they are or want to be have co-opted that group.
There's a new movement in autism awareness to focus on "intersectionality", to focus or at least bring light to how autism affects specific sections or groups of people (e.g. racial, sexual, gender, etc) in ways that may not affect autistic people who are not in those groups. In theory I see nothing wrong with that. Also, in practice I see nothing wrong with it either; however...in my own personal experience with being part of an autism group and participating in a state level autism organization, the tendency is that more vocal "intersectional" groups can co-opt the autism community at large which can end up doing the same (becoming exclusive rather than inclusive) which was the opposite of its supposed intent. And that's wrong.
You mention ASAN and they're an example I'd give which speaks to a trend of purporting to be inclusive (ie advocating for all autistic people) but actually being exclusive. ASAN is a political organization which again purports to be for all autistic people but clearly it has a very "left leaning" political stance. While I personally do not consider myself to be either "left leaning" or "right leaning", a "left leaning" organization is exclusive to "right leaning" autistic people. If the organization purports to be for ALL autistic people but is critical of, opposed to or even against those with political ideologies that differ from the organization's, that's wrong.