Just quit my job because of how I speak

Just quit my job because of how I speak I'm 16 and i have a moderate stutter. I work in an ice cream restaurant where i scoop ice cream and take peoples carry-out orders. Today a women was upset that she didn't get enough chicken fingers. I tried to say, "that's the portion size" but i couldn't spit it out so i just ran in the back and told the manager to take care of it. It's instances like these that made me quit my first job after less than a month.