I am in a similar position to you (i got a U in two subjects out of the four i do). I think you should talk to your teachers and ask if there's any way to make your predicted grades higher like maybe do a mock? Or even think about another course you would like to study. But tbh the best thing you could do is talk out all the options you have with your teachers and what they think is best for your future career. Also, would your college allow you to continue chemistry with a U?