My AF comes like clockwork. Always the end of the month( either 30 or 31st) well glow predicted it coming on 1-28 and it never showed. So I told glow I was late and it moved it to the 31st. Well 31st is here and nothing....put it in the app and again moved it to 2nd of feb. My period is never late and I took a pregnancy test this afternoon and it was negative. I didn't use FMU so I'm not sure if I should be hopeful or see a doctor. Any advice of help??