Nervous

If I’ve had MULTIPLE BFN’s and a 2 periods (2 days heavy and filling tampons, 1 very light day), is it safe to say I’m not pregnant? I don’t have any symptoms, but can’t stop thinking I could be one of those rare cases where someone doesn’t know. Don’t know why I can’t let go of the anxious feeling. Any insight or comfort would be helpful! Thx!