I too experience this on a daily basis. Although I feel comfortable around my parents, I actually have blocks around them the most. With close friends, I probably experience my best fluency. And as far as strangers, saying my name/introducing myself is always a struggle. Even while I'm ordering food I have blocks. Having blocks around strangers makes sense to me, but I'm confused why I have them around my parents so much. Stuttering is a great mystery to me.