Negative 3 days before af. Positive test on day af due?

Has anyone gotten a bfn a few days before af and then a positive on the day of? I am currently 3-4 days away from af. Experiencing some nausea, headaches and increasing cm that looks like lotion. The last one being the most unusual for me and has only happened in previous pregnancies. No living children. :( i tested today and thought I may have seen the faintest of lines. Maybe I have line eyes and wishful thinking. Looking for some positive stories from you ladies that this might have happened to before? I know they say you aren’t out until af shows, but it’s hard to stay positive!