Saturday afternoon I took a first response pregnancy test and it came up positive - strong positive. done one a couple hours later, positive came up within 30 seconds. did a clear blue digital the same day, said not pregnant so I waited until the next day to use my morning wee and it said not pregnant? my last period was on 18th July. I was bleeding for 2 days lightly 1st-3rd August - I thought this was another period but now I'm starting to think it was implantation bleeding. has this happened to anyone else and they have been pregnant??