Is NOBODY wrong in the post ? POST : Sorry for my poor english.

I have always been slightly sosial awkward, and normally dont take much part in setting opp parties or arrangements with familiy. Whenever sombody asks me to go get this, or drive there buy this, i do that i an instant, no arguments about how far i need to drive or how much something costs. But I only do stuff when asked. My sister came to me today and said that she thinks i dont participate in arrangements enough. She said that its is always here or my other sister who orders and pays for stuff like cakes and such for events around our parents. I didnt argue with here about that, because they always have arranged stuff like this, and i kind of become a "middel man". I drive and get the cake, pick up my sisters, or get items they need, and if it is not paid for i just pay for it, no questions asked. But i told her that, even though i dont take inititativ in arrangements by buying the cakes, or order them or other items, i help as much as i can in other areas. Neither of my sisters drive anywhere, whenever something is needed, i drive, and that also means i maintain the car that alle 3 of us use. Pay the gas, maintenance and other necessitis. I always thought that my contribution by beeing this "middel man" was more then enough.

So i am wondring am i in the wrong here? Am i the Asshole for always letting my sisters the initiativ in arrangmentes and order things and then just fill the gaps?