First of all, it's completely okay to be frustrated with it. Anyone would be and most of us are at some point. But I would say that you probably shouldn't look to a career for fulfillment or self expression. Most of us, stutterers or not, work because we have to. I'd suggest finding a hobby that expresses yourself. For me it was music and writing. There was an ad I saw once for a guitar that hit the nail on the head, "I can't tell you but I can it for you."