student needing suggestions

I am a student in an online master's program. The instructor deducted points from last's week discussion board because she said I had not answered her questions. She had asked 2 questions in about my initial post. I did answer her the best I could. So I emailed her and said that I had answered, though maybe I had not given the answer she needed, and that I would try to be more specific next time. Her reply was short, just to tell me to sign my emails as instructed. I didn't know I was to sign them any certain way. Knowing she has many students, I had put my full name and the specific course I am in. Now I am not sure what to do b/c it feels like I have made her angry. She seemed snappy that last time I "spoke" with her. I am afraid to email again for any reason. Any suggestions? Maybe she is just tired.