Delay in periods, the reasons are many:
Stress,
PCOS
obesity,
excessive exercise,
medication,
hormonal imbalance,
thyroid disorder.
Next Steps
I would advice you to take USG scan and do inform me or consult a nearby doctor with the report.
Health Tips
if you are obese, do keep a regular checkup of your weight.
try to avoid unnecessary medication specially to regulate hormones.
Stress is a main factor which surely disturbs the harmonious flow of one's vital energy.so, keep your mind calm.