Autistic...or just odd?

Hi everyone,

I'm in my mid twenties and finding things harder than ever. I really struggle with social skills and although I've always been told I'm "just shy" I've always known something is not right. Despite having outgrown the awkward teenage years I still find it incredibly difficult and confusing holding a conversation with pretty much everyone apart from very close family, even some friends I've known for years. 

I've never been like other people, with strong interests and beliefs, not understanding or agreeing with social norms but recently become more aware of just how odd I am (must look for patterns in reg numbers, must always have car windows open even in January! etc...). I think I might be autistic but I'm terrified of going for a diagnosis to be laughed at and told l am just shy and a bit strange. I work with autistic people and although realise it's a spectrum disorder, I am nowhere near as affected as them. I think I probably come across as a little eccentric, lacking in self confidence and very shy.

I am really struggling with self confidence and self doubt and think a diagnosis would probably pull me out of the hole I've dug for myself; but am I just socially awkward, unusual, and looking for something to take the blame?

I guess I'm asking how autistic do you need to appear to get a diagnosis??!