I'm sure you'll be able to pick up French relatively quickly. Once you learn to 'multi think' or translate things in your head for one language, learning more becomes easier.
Mandarin was a good choice, it could help you in many careers. I took four years of Latin and while I enjoyed it, I could have picked something more useful. It did help me understand all theRomance languages on at least a rudimentary level, which has been helpful.