Confused 🤷🏽‍♀️

Claire

So..... I was due AF 10/4/18 and nothing came, then 11/4/18 I had terrible cramps and a standard first day AF, then Iv had nothing since (it’s normally 3 days I have it) I’m now thinking was this maybe implantation bleed? Although my BBT dropped as it would before AF and has only slightly raised again! Feel like I’m being stupid and over thinking everything! But Iv honestly never had a 1 day AF before! Anyone had this? Thanks in advance.