People keep telling me that I am slow.?

I am male and 17 and people keep telling me that I am slow. I don't think I am slow I am just lazy, I am not over weight I am infact incredibly skinny. I for some reason can't think fast enougf or anything. I have horrable concentration I always get thigs stuck in my head such as music or scenes od movies. My parents say I have Aspurgers but I don't know. I am told that my reflexes are terrible and that I am slow. I was wondering does me being slo have to do with my arm strenght? because I cant cach a ball or try to quickly grab something that fast. I was wondering how can I be faster?