My assessment deemed I am not autistic, feel it was wrong

I had an assessment for autism around 2.5 years ago and the outcome was that I am not autistic. However, I feel like I relate so much to the information on line in particular around difficulties interacting, scripting conversations, and just feeling 'different' to everyone else. However, I feel like in my assessment I masked (although I still don't really understand what masking is aside from trying to fit in with people around me... but I am not sure exactly what I do / say to do this) and overemphasised social anxiety feelings/symptoms and didnt advocate for myself. 

I am not sure what to do now as I am really struggling with anxiety but feel like this is due to not being able to be my authentic self - and I do not understand who that is. Is it possible to try and get another diagnosis? (I expect not) - or would it be worth trying to get some therapy/counselling on the basis of autism? or should I trust that the (non)-diagnosis was correct? I have in the past few months been diagnosed with ADHD (aged 32, female) and do think I have this, but I do not feel that it is *everything*...

Any advice would be much appreciated

Thanks