Why is it that if someone calls me early in the morning before so I am up, my stuttering is so terrible?

Why is it that if someone calls me early in the morning before so I am up, my stuttering is so terrible? Whenever I get woken up by a phone call I can never speak the slightest bit of fluency, well mostly I can't. Just a half hour ago my boss called to tell me I need to come in a couple hours early and I could barely say one word. I could only say "10 am" fluently and all the other words I blocked and repeated over and over. Sometimes I just want to stop talking altogether but with my job that would be nearly impossible. After all this time I still can't resolve myself to keep thinking in a positive mindset. Sure, there are people I will meet on occasion who have outgrown their stutter and applaud me for taking such a high stress job. There was a dad who had his young son with him who had started stuttering recently and saw no future for himself until he met me. Those times make me see for a short while that my life does have some purpose. So it seems. Then as times passes, a day, few days or a week, and I realize there is no point to this. I started stuttering when I was nine and now at twenty two I am seriously losing hope that there is ever a chance at me gaining any fluency. Without being able to properly communicate with people how am I ever suppose to start my career? At this point the only career I see is working in the fast food industry for the rest of my life.