Yes, I was like that too, that's why writing out what I'm going to say and reading it helps me. Maybe think ahead to possible responses she'll have or what it will be like when she calls back (if you get an answering machine). I often surround myself with paper and pen, a calendar, any notes about what I'm doing, when, my daily schedule even, so I can easily decide if a certain time to meet will be okay. Even a map, in case she's moved and has a different address. I write down what they say when they talk to me because I have a hard time "hearing"/making sense of it, get too anxious.

Pretend it's a business call? Pretend she's one of your stores, LOL.