Well, that's a pretty poor effort on the doctor's part. "You aren't able to make friends because you're an aspie". How ridiculous. If a doctor told me that, well...I wouldn't go back to see him again, that's for sure.
No friends is a tough gig, I know. But don't believe for one second that it's impossible to make them because of Aspergers.
I've met most of my friends in my classes at university, but it's also a good idea to try connecting with people through volunteer activities or work. Maybe try starting your own club. Find something you're interested in and put a flier around asking for expressions of interest.