Ask yourself thsese questions:
Do you find social situations confusing?
Do you find it hard to make small talk?
Do you tend to turn any conversation back onto yourself or my own topic of interest?
Are you good at picking up details and facts?
Do you find it hard to work out what other people are thinking and feeling?
Can you focus on certain things for very long periods?
Do people often say that you were rude even when this was unintentional?
Do you have unusually strong, narrow interests?
Do you do certain things in a very inflexible, repetitive way?
Have you always had difficulty making friends?
If you answered "Yes" to most of these questions, then that is probably why. Thsese are all signs of Autism.