I've been charting my BBT for quite some time, I'm on day 29 of my cycle (which usually runs an average of 30 days) and I took a home pregnancy test (Answer Quick & Simple Early Pregnancy Test) on day 28 which is supposed to predict pregnancy up to 4 days before your missed period and I tested negative...I had light spotting (more like staining) on day 15 with none since and I have read that a BBT of 98.1-98.5 this late in my cycle would signify pregnancy but my test was negative..any thoughts???