When would you expect a person to be articulate?

When I get very nervous or excited I have trouble speaking well and talk too fast and say the wrong thing. When I had a job interview I was like this. I know they were expecting more but I was so terribly nervous and excited all at once that I could not perform to the best of my ability. I am a competent person, honestly. I just get terribly nervous and excited and anxious all at once. (I have a medical condition) I went to the doctor and saw a new doctor. They knew what I had and still asked me hard questions I had to think really hard about and once again I got flustered. In what situations would you expect a person to be very articulate? Forgot to mention, during college I got nervous speaking in front of the cl and the cl mates judged me and I was told did not like me. I am embarred by all this but it is really not my fault. I do the best I can.