Autism and Depression/Bipolar II

My current psychiatrist says I am autistic and has referred me for assessment (I'm 51).

I have suffered recurring depression all my life, and now recognise some of this is due to autistic burnout.

His diagnosis is ?Bipolar II .

Is this a common autistic co-morbidity?

My main issues with depression is low self esteem, perfectionism, inability to socialise/make friends (loneliness, not enjoying being with crowds or no interest in 'usual' social things). I just feel useless/a failure having tried so hard to fit in and failed. 

How do I find out if any of my issues are because of autism, and how do I drag myself out of depression if they are? 

Sorry to be miserable :-(

TIA