Maybe you could try volunteering for a crisis line to see how you cope with/ enjoy helping other people who have MI. over here we have short courses that you can do to volunteer on those hotlines and they count towards counselling diplomas.
I think it's a good idea to try out what you want to study for before you commit to it cos you don't want to spend years studying only to hate what you do. I speak from experience
I think clin psych or counselling would be a better fit than med though psych nurse might also be good. Just be aware that they are all stressful jobs.