Take a pregnancy test
If you period is late take a pregnancy test. If the test is negative then wait another week and if you still haven't gotten your period take another test. If that test is negative you should schedule an appointment with your doctor to make sure you don't have any underlying medical issues.
Various reasons can cause your cycle to be irregular such as late ovulation, hormone imbalance, ovarian disorders, stress, etc. Your doctor will be able to explore the possibilities with you and suggest a possible treatment.
Not all women will have pregnancy signs and symptoms so the only way to know for sure is to take a test.