Calling People/Voicmail

I hate talking on the phone in general but leaving voicemails is the worst! I will talk myself through calling someone for about an hour before I can make a call but if I get a voicemail I lose it all. I fumble over everything, am totally awkward like I have no idea how to communicate with people, and never know how to end it. I am so down on myself after leaving one and feel like such an idiot. I have no idea how to fix it either. Seriously I feel so dumb. I had to call a blood lab and a doctor's office about prices (it's not covered by insurance and is expensive so I wanted to compare prices), call my main doctors office, and set up an appointment for fixing a fraying seatbelt in our car today. I got voicemails for every single one of those places. They called me back about what I left a voicemail for but I hate it all. When I'm on the phone my heart is racing, my hands are shaky, and I have to focus solely on the phone call and nothing else. I thought it would be easier the more I have to do these sort of things but I'm 27, 28 next week, and it's not at all easier. Ugh! What's wrong with me?!