My boyfriend is shy around me? ?

I've been dating my boyfriend for just over a month, but Ive known him since elementry school. When we hang out, we can never find anything to talk about, and he seems nerves around me when he never used to be. He hasnt kissed me yet, and we hardly touch at all. I'm also nothing like the girls he hangs out with (they're plastic and pretty and I'm not). I've liked him for a while, but haven't told anybody. I honestly have no clue why he asked me out. Hes my first boyfriend (but I don't think he knows he is), so I have no experience.