One of the most helpful things anyone ever told us was that the absence of 'friends' for an autistic child is the parent's problem, not the child's. People 'on the spectrum' function differently especially within a social context and the need for interaction outside of the people upon whom they rely, can be extremely limited.
From first hand experience, it is really hard to get your head around. At the age of 22, my son has friends but he has no burning desire to see them all the time. They usually hook up once a year and he is 100% comfortable with that. I think you have to understand that seeing people for the sake of it, for company etc, is of little relevance if it doesn't serve some function. By this, I mean 'I want to see X because I want to tell him something special' rather than, 'I want to see X so we can just hang out'.
What we discovered was that our son made constant progress towards achieving some sort of functionality within 'our world', but the steps were often very, very small. Keep an eye out for them with your child, they are worth their weight in gold.