Hello!
There are a variety of factors that can cause your period to be late, other than pregnancy.
For instance, if your life has been particularly more stressful recently, your period may be late. If you've lost weight over the last few weeks, that can affect your periods. Perhaps you are taking or have taken other medicines which are affecting either the birth control pills, or your periods. Do you feel well? Sometimes just the stress of a cold or an infection can affect when your periods occur.
It may not be a bad idea to see your OB/Gyn to be evaluated, and to have a pregnancy test done in the office, which is often much more accurate than home pregnancy tests.
Good luck. If this helps, please ACCEPT my answer. Thanks.