Sometimes the periods can be delayed because of the hormonal issues as well and not necessarily only due to pregnancy.To test for the pregnancy you can test with the home pregnancy kit on the day of the missed period and repeat the test after a week of the date of the missed period.
Next Steps
If the test comes out to be positive then you should get one ultrasound scanning done which is called the early pregnancy scan to localise the pregnancy whether it is at its correct place that is the uterus.