I had unprotected sex on December 20th, we used the pull out method, my fertile window started on the 23rd and ended the 29th. One app I have said I was due two days ago, one said I was due yesterday. So I bought the first response pregnancy test, both were negative. Later on today I started to bleed, what looks like my period. My period always starts off light, and at a dark brown color. However, I haven’t had any more bleeding yet today and don’t have many cramps like I normally do. Could this be implantation bleeding or am I being paranoid?