Can social anxiety disorder develope at an older age, like 12?

And if so what causes it? I feel like I was a very normal kid socially, then around the age of 12 I started to feel nervous all the time and I felt socially awkward. It seemed like it happened right around the same time I started liking girls too and after that I seemed to be extra nervous and shy around girls. Did puberty cause me to get social anxiety disorder? Because before I liked girls I never felt that type of social anxiety at all in my life.