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I believe it would be best for you to start again as a mathematician, the reason is not far fetched you'll end up pleasing your loved ones (mom, girlfriend and friends) and also please yourself by continuing with the business and getting a good CGPA. You never know when the degree will come in handy as it is said that no knowledge is a waste. The job opportunities for a mathematician are much, perhaps the first that comes to the mind of most people;
1 Lecturers or secondary school teachers
2 Chartered accountants
3 Mathematical Research scientists(who knows your services might be needed on a spaceship).
My point is do whatever makes you happy, it'll pay off.

You were only studying Chemical Engineering b/c your parents wanted you to and it wasn't / isn't your passion. Based on your post it seems you hated Chem Eng. If you know you're good in Mathematics, then that's what you should study. Having a good GPA is extremely important.