A gap like this after fairly regular cycles is usually not PCOS when there's no weight gain, acne or excess hair, as you've described. More likely causes at your age are stress, a change in weight or routine,
thyroid levels, or your body taking a while to settle back into ovulation after the emergency contraception you took in March.
Next Steps
Take a home
pregnancy test first to rule that out, and if it's negative, ask for a
thyroid and
prolactin blood test if your period hasn't returned in the next two to three weeks.
Health Tips
There's no reliable way to bring periods back naturally without knowing the cause first, so please see a gynaecologist for an in-person evaluation and a pelvic ultrasound if this continues.