Are you worried that if you write about several things he will feel obligated to answer them all in writing? Or are you worried that he won't want to read a long e-mail? Put yourself in his shoes and ask those questions, how would he respond? I bet he would say well, just write about how you are feeling. He will let you know if he cannot respond to all issues by e-mail. Why not write to him at the same time you would be in his office. Meditate for a minute or so first and then write about the first thing that comes up. Good luck!