There is no need to worry about using retainers. But when your start wearing it, initially you might have some discomfort, in wearing, eating and also in speaking . Your exams are most critical .
My personal advise is keep your braces till exams are over then you can change your removable retainers.
If you are going for fixed retainers then no issues.
Next Steps
Meet you dentist and asks the pros and cons of the retainer then decide ..
Health Tips
brush your teeth twice daily
use mouth wash regularly
meet your dentist once in six months .