I had to learn it, explicitly, as an adult. This is part of 'emotion regulation' in DBT, and there are some fab handouts, which list each emotion, and the situations in which you might feel it, how you might feel in your body, what your thoughts might be, what your action urges might be, how you might feel once the emotion is gone... It's basically detective work at first, starting with your action urge (e.g. to SI) and going through the sheets until you find an emotion that fits! But it gets easier, and it's such a helpful skill to have.

Hope you feel a bit better in the morning, and that your T replies soon