Is it normal to only have male friends because..

Is it normal to only have male friends (as a woman) because I feel less nervous with men because there is no chance of sex with them? I have never wanted to have sex with a man i've spent lots of time with even if I found him attractive, and even if he wanted to have sex with me. Does this mean i'm not straight?? When an attractive woman talks to me though I cant even look at her because I feel like a creep and like she can tell and it makes me blush and act weird!!!!