I think that starting the conversation about what to do in your life with marks from school is a huge mistake. What will make you successful and happy is working on something you are passionate about, marks may show aptitude but they don't tell you much more than that. Not to mention your experience in these classes probably far from demonstrate what it is actually like to work in any of these fields. You need you get out there, gain experience, meet people. People can be successful in an field, so Lon as they have the passion to go the distance.