You have not mentioned how many days you were late for your periods? If gap between your 2 periods was more than 35 days then it is abnormality. Otherwise, it is normal. Delay in periods can be due to following reasons.
- Pregnancy and lactation
- Hormonal imbalance
- Thyroid and pituitary gland problems
- Chronic illness
- Side effects of some medicines like antidepressants
- Excessive exercise