Chemistry or Applied Math? Is it worth double majoring?

I am in my third undergrad year at a small university. I recently decided to change my major, but I can’t decide if I should settle on applied mathematics or chemistry(general). I have credits that count towards both and would still be able to graduate in four years(total) for either, and I currently have an internship that makes more sense for a math major. I would need to take an extra semester if I were to double major, however, and I’m not leaning towards either major. I have a lot of questions pertaining to all three scenarios.
Is it worth taking that extra semester to graduate for the double? How would this affect graduate school/the job search if I graduate in the winter? And how would choosing one major over the other affect me as far as graduate school/finding a job out of undergrad goes? I’m interested in energy development as a potential career field.