Not very good advice I am afraid. I know of no astronomers who were weak in math and physics that can now boast of getting a PhD and winning a secure professional future. You're best bet is to look into space-related careers, for example, public relations, and working at planetaria. I do not know of specific, alternate careers in space science or education and what their minimum skill requirements are, so I am afraid you will have to do a bit of serious detective work. Good luck, and I am sure you will find something, but please make certain that your goals are really in line with your skills .This avoids a LOT of frustration later on. Believe me.