There's a great thread located here that you may want to readbut it seems like no one else can comfort her, but me.
That said, it's alright to be the sole source of comfort for your baby, especially one that is only 3 weeks old. Try to look at it from your baby's perspective -- it wasn't very long ago that she was nestled snugly in a very warm, very quiet and very soothing environment. Then, one day she was suddenly in a very different environment. You, as her mommy, are the only familiar thing to her. Your breasts provide not only nourishment but comfort as well. You aren't a pacifier. You are a comforter and there's absolutely nothing wrong with a baby forming an attachment to a real live human being over an inanimate or plastic object
Many mom's find that if they can nurse baby in a sling that they've got more mobility and that helps ease those feelings of frustration at not being able to do anything than sit and nurse.
(((HUGS))) You're doing a great job! Trust your body and your baby -- they've got this nursing deal figured out!