Has anyone ever got BFNs and then a late BFP?

I'm currently about a week-week and a half late on AF. No idea when I ovulated or if I even did. But what I can tell you is my symptoms...2 weeks ago I had mild cramping and sore boobs...thought it was AF coming...never did. So I waited. Then I got extremely fatigued...so much so that I was napping during the day. The fatigue is still there but not as bad some days. Now today I noticed increased creamy CM..sorry for the TMI. I have taken 3 first response tests and all are BFN...some people think there is a vvvvvvvvfl but honestly probably just bfn. Has this ever happened to anybody before? Also the last 3 days I am a little nauseous on and off throughout the day and have an on and off headache...that all sounds like prego or AF symptoms to me but I don't have either!!!! I am so confused and am sick of the emotional rollatcoaster.

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