HELP I DONT WANT TO BE PREGNANT

My period is very regular. I’m 4 days late today and have negative pregnancy test. With my first two pregnancies I got positive results before my period was even due. I just want peace of mind more than anything else do I believe the test? Why is my period late or not coming this month? Has anyone ever experienced a missed period for the first time and ended up NOT pregnant? (Not on any medications, or any form of birth control and I know the irresponsible aspect of this all, if I’m not pregnant this was definitely a lesson for me and I will be getting on it)