Very confused

So my period is three days late today. I started birth control about three months ago. My doctor told me that because my flow was already pretty light that it was possible I wouldn’t even have a period. I had one last month but it was even lighter then normal and it was more of a discharge then blood. I took a test then because I was nervous it was implantation bleeding it came back negative. So here I am now without a period. I haven’t had intercourses since before my last kinda period in July but I have messed around with my boyfriend and I am always concerned about precum. Since I’m three days late I took a test this morning and it was negative. Do you guys all think I’m in the clear or do you think that there might be a chance of pregnancy and I’m just testing too early? How do I not stress over this possibility of not having a period to confirm that I’m not pregnant?